Publications

† : Equal contribution * : Corresponding author.

2025

1. Nanoscale

   

   Mathematically inspired structure design in nanoscale thermal transport

   Xin Wu^*, and Masahiro Nomura^*

   Nanoscale, Jan 2025

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   Mathematically inspired structure design has emerged as a powerful approach for tailoring material properties, especially in nanoscale thermal transport, with promising applications both within this field and beyond. By employing mathematical principles, based on number theory, such as periodicity and quasi-periodic organizations, researchers have developed advanced structures with unique thermal behaviours. Although periodic phononic crystals have been extensively explored, various structural design methods based on alternative mathematical sequences have gained attention in recent years. This review provides an in-depth overview of these mathematical frameworks, focusing on nanoscale thermal transport. We examine key mathematical sequences, their foundational principles, and analyze the influence of thermal behavior, highlighting recent advancements in this field. Looking ahead, further exploration of mathematical sequences offers significant potential for the development of next-generation materials with tailored, multi-functional properties suited to diverse technological applications.

   @article{Nanoscale_minireview,
     author = {Wu, Xin and Nomura, Masahiro},
     title = {Mathematically inspired structure design in nanoscale thermal transport},
     journal = {Nanoscale},
     volume = {17},
     pages = {3003-3013},
     year = {2025},
     month = jan,
     issn = {0021-8979},
     doi = {10.1039/D4NR04385E},
     url = {https://doi.org/10.1063/5.0058715},
     eprint = {https://pubs.aip.org/aip/jap/article-pdf/doi/10.1063/5.0058715/13252743/124401\_1\_online.pdf}
   }

2. PRB

   

   Phonon coherence and minimum thermal conductivity in disordered superlattices

   Xin Wu, Zhang Wu, Ting Liang, Zheyong Fan^*, Jianbin Xu, Masahiro Nomura^*, and Penghua Ying^*

   Physical Review B, Feb 2025

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   Phonon coherence elucidates the propagation and interaction of phonon quantum states within superlattice, unveiling the wavelike nature and collective behaviors of phonons. Taking MoSe2/WSe2 lateral heterostructures as a model system, we demonstrate that the intricate interplay between wavelike and particlelike phonons, previously observed in perfect superlattice only, also occurs in disordered superlattice. By employing molecular dynamics simulation based on a highly accurate and efficient machine-learned potential constructed herein, we observe a nonmonotonic dependence of the lattice thermal conductivity on the interface density in both perfect and disordered superlattice, with a global minimum occurring at relatively higher interface density for disordered superlattice. The counterintuitive phonon coherence contribution can be characterized by the lagged self-similarity of the structural sequences in the disordered superlattice. Our findings extend the realm of coherent phonon transport from perfect superlattice to more general structures, which offers more flexibility in tuning thermal transport in superlattices.

   @article{10.1103/PhysRevB.111.085413,
     author = {Wu, Xin and Wu, Zhang and Liang, Ting and Fan, Zheyong and Xu, Jianbin and Nomura, Masahiro and Ying, Penghua},
     title = {Phonon coherence and minimum thermal conductivity in disordered superlattices},
     journal = {Physical Review B},
     volume = {111},
     pages = {085413},
     year = {2025},
     month = feb,
     issn = {0021-8979},
     doi = {10.1103/PhysRevB.111.085413},
     url = {https://doi.org/10.1103/PhysRevB.111.085413}
   }

3. MGEA

   

   GPUMD 4.0: A high-performance molecular dynamics package for versatile materials simulations with machine-learned potentials

   Ke Xu^†, Hekai Bu^†, Shuning Pan, Eric Lindgren, Yongchao Wu, Yong Wang, Jiahui Liu, Keke Song, Bin Xu, Yifan Li, Tobias Hainer, Lucas Svensson, Julia Wiktor, Rui Zhao, Hongfu Huang, Cheng Qian, Shuo Zhang, Zezhu Zeng, Bohan Zhang, Benrui Tang, Yang Xiao, Zihan Yan, Jiuyang Shi, Zhixin Liang, Junjie Wang, Ting Liang, Shuo Cao, Yanzhou Wang, Penghua Ying, Nan Xu, Chengbing Chen, Yuwen Zhang, Zherui Chen, Xin Wu, Wenwu Jiang, Eséee Berger, Yanlong Li, Shunda Chen, Alexander J. Gabourie, Haikuan Dong, Shiyun Xiong, Ning Wei, Yue Chen, Jianbin Xu, Feng Ding, Zhimei Sun, Tapio Ala-Nissila, Ari Harju, Jincheng Zheng, Pengfei Guan^*, Paul Erhart^*, Jian Sun^*, Wengen Ouyang^*, Yanjing Su^*, and Zheyong Fan^*

   Materials Genome Engineering Advances, Aug 2025

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   This paper provides a comprehensive overview of the latest stable release of the graphics processing units molecular dynamics (GPUMD) package, GPUMD 4.0. We begin with a brief review of its development history, starting from the initial version. We then discuss the theoretical foundations for the development of the GPUMD package, including the formulations of the interatomic force, virial and heat current for many-body potentials, the development of the highly efficient and flexible neuroevolution potential (NEP) method, the supported integrators and related operations, the various physical properties that can be calculated on the fly, and the GPUMD ecosystem. After presenting these functionalities, we review a range of applications enabled by GPUMD, particularly in combination with the NEP approach. Finally, we outline possible future development directions for GPUMD.

   @article{gpumd4,
     author = {Xu, Ke and Bu, Hekai and Pan, Shuning and Lindgren, Eric and Wu, Yongchao and Wang, Yong and Liu, Jiahui and Song, Keke and Xu, Bin and Li, Yifan and Hainer, Tobias and Svensson, Lucas and Wiktor, Julia and Zhao, Rui and Huang, Hongfu and Qian, Cheng and Zhang, Shuo and Zeng, Zezhu and Zhang, Bohan and Tang, Benrui and Xiao, Yang and Yan, Zihan and Shi, Jiuyang and Liang, Zhixin and Wang, Junjie and Liang, Ting and Cao, Shuo and Wang, Yanzhou and Ying, Penghua and Xu, Nan and Chen, Chengbing and Zhang, Yuwen and Chen, Zherui and Wu, Xin and Jiang, Wenwu and Berger, Es{\'e}ee and Li, Yanlong and Chen, Shunda and Gabourie, Alexander J. and Dong, Haikuan and Xiong, Shiyun and Wei, Ning and Chen, Yue and Xu, Jianbin and Ding, Feng and Sun, Zhimei and Ala-Nissila, Tapio and Harju, Ari and Zheng, Jincheng and Guan, Pengfei and Erhart, Paul and Sun, Jian and Ouyang, Wengen and Su, Yanjing and Fan, Zheyong},
     title = {GPUMD 4.0: A high-performance molecular dynamics package for versatile materials simulations with machine-learned potentials},
     journal = {Materials Genome Engineering Advances},
     volume = {000},
     pages = {e70028},
     year = {2025},
     month = aug,
     doi = {10.1002/mgea.70028},
     url = {https://doi.org/10.1103/PhysRevB.111.085413}
   }

2024

1. JAP

   

   Molecular Dynamics Simulations of Heat Transport Using Machine-Learned Potentials: A Mini-Review and Tutorial on GPUMD with Neuroevolution Potentials

   Haikuan Dong^*, Yongbo Shi, Penghua Ying, Ke Xu, Ting Liang, Yanzhou Wang, Zezhu Zeng, Xin Wu, Wenjiang Zhou, Shiyun Xiong, Shunda Chen^*, and Zheyong Fan^*

   Journal of Applied Physics, Apr 2024

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   Molecular dynamics (MD) simulations play an important role in understanding and engineering heat transport properties of complex materials. An essential requirement for reliably predicting heat transport properties is the use of accurate and efficient interatomic potentials. Recently, machine-learned potentials (MLPs) have shown great promise in providing the required accuracy for a broad range of materials. In this mini-review and tutorial, we delve into the fundamentals of heat transport, explore pertinent MD simulation methods, and survey the applications of MLPs in MD simulations of heat transport. Furthermore, we provide a step-by-step tutorial on developing MLPs for highly efficient and predictive heat transport simulations, utilizing the neuroevolution potentials as implemented in the GPUMD package. Our aim with this mini-review and tutorial is to empower researchers with valuable insights into cutting-edge methodologies that can significantly enhance the accuracy and efficiency of MD simulations for heat transport studies.

   @article{Dong_2024_Molecular,
     title = {Molecular Dynamics Simulations of Heat Transport Using Machine-Learned Potentials: A Mini-Review and Tutorial on GPUMD with Neuroevolution Potentials},
     author = {Dong, Haikuan and Shi, Yongbo and Ying, Penghua and Xu, Ke and Liang, Ting and Wang, Yanzhou and Zeng, Zezhu and Wu, Xin and Zhou, Wenjiang and Xiong, Shiyun and Chen, Shunda and Fan, Zheyong},
     year = {2024},
     month = apr,
     journal = {Journal of Applied Physics},
     volume = {135},
     number = {16},
     pages = {161101},
     doi = {10.1063/5.0200833},
   }

2. MTP

   

   Isotope Interface Engineering for Thermal Transport Suppression in Cryogenic Graphene

   Xin Wu^*, Yunhui Wu, Xin Huang, Zheyong Fan, Sebastian Volz, Qiang Han^*, and Masahiro Nomura^*

   Materials Today Physics, Aug 2024

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   The development of emerging technologies, such as quantum computing and semiconductor electronics, emphasizes the growing significance of thermal management at cryogenic temperatures. Herein, by designing isotope interfaces based on the Golomb ruler, we achieved effective suppression of the phonon thermal transport of cryogenic graphene. The pronounced disordering of the Golomb ruler sequence results in the stronger suppression of thermal transport compared to other sequences with the same isotope doping ratio. We demonstrated that the Golomb ruler-based isotope interfaces have strong scattering and confinement effects on phonon transport via extensive molecular dynamics simulations combined with wave packet analysis, with a proper correction for the missing quantum statistics. This work provides a new stream for the design of thermal transport suppression under cryogenic conditions and is expected to expand to other fields.

   @article{Wu_2024_Isotope,
     title = {Isotope Interface Engineering for Thermal Transport Suppression in Cryogenic Graphene},
     author = {Wu, Xin and Wu, Yunhui and Huang, Xin and Fan, Zheyong and Volz, Sebastian and Han, Qiang and Nomura, Masahiro},
     year = {2024},
     month = aug,
     journal = {Materials Today Physics},
     volume = {46},
     pages = {101500},
     doi = {10.1016/j.mtphys.2024.101500},
   }

2023

1. IJHMT

   

   Dual Effects of Hetero-Interfaces on Phonon Thermal Transport across Graphene/C3N Lateral Superlattices

   Xin Wu, Penghua Ying, Chunlei Li^*, and Qiang Han^*

   International Journal of Heat and Mass Transfer, Feb 2023

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   Two-dimensional (2D) lateral superlattices, a typical artificial nano-phononic crystal, have stimulated widespread interests and potential application prospects in terms of their physically interesting features. Herein, we have found wave-particle crossover of phonon transport in the graphene (Gr)/2D polyaniline (C3N) lateral superlattices, which is an indication of a transition in the phonon transport mechanism from the incoherent to coherent regime. Due to the high structural similarity of C3N to Gr, the thermal conductivity of the Gr/C3N lateral superlattice can achieve an ultra-wide modulation range of about W/mK, which is far beyond that of other superlattices. The analysis shows that an increase of the interface density will on the one hand weaken the thermal conductivity by increasing phonon-interface scattering, and on the other hand increase it by lowering the phonon transport barriers and allowing more long-wavelength phonons to participate in the transport. This determines the parabolic trend of thermal conductivity containing the minimum, and also reflects the dual effects of hetero-interfaces on phonon thermal transport. In addition, phonon calculations show that the above variation in thermal conductivity is entirely attributable to differences in the phonon mean free path for different interface densities and is not related to their group velocity.

   @article{Wu_2023_Dual,
     title = {Dual Effects of Hetero-Interfaces on Phonon Thermal Transport across Graphene/C3N Lateral Superlattices},
     author = {Wu, Xin and Ying, Penghua and Li, Chunlei and Han, Qiang},
     year = {2023},
     month = feb,
     journal = {International Journal of Heat and Mass Transfer},
     volume = {201},
     pages = {123643},
     doi = {10.1016/j.ijheatmasstransfer.2022.123643},
   }

2. Carbon

   

   Suppressed Thermal Transport in Mathematically Inspired 2D Heterosystems

   Xin Wu^*, Xin Huang, Lei Yang, Zhongwei Zhang, Yangyu Guo, Sebastian Volz, Qiang Han^*, and Masahiro Nomura^*

   Carbon, Sep 2023

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   In two-dimensional (2D) heterosystems, the contribution of coherent phonon transport makes superlattices with high interface density exhibit unexpected high thermal conductivity. Herein, inspired by mathematics, we demonstrate efficient suppression of phonon thermal transport in a 2D heterosystem constituted of graphene and hexagonal boron nitride based on the Golomb ruler sequences. This design realizes extreme suppression of thermal conductivity with a minimal number of interfaces, and without any defects or dopants. Extensive numerical simulations combined with wave packet analysis show that the Golomb ruler sequence largely cancels the coherent phonon transport. This work, as the first attempt for realizing novel thermal physics using the mathematically inspired Golomb ruler design, provides a new and efficient solution for the suppression of thermal transport in 2D heterosystems.

   @article{Wu_2023_Suppressed,
     title = {Suppressed Thermal Transport in Mathematically Inspired 2D Heterosystems},
     author = {Wu, Xin and Huang, Xin and Yang, Lei and Zhang, Zhongwei and Guo, Yangyu and Volz, Sebastian and Han, Qiang and Nomura, Masahiro},
     year = {2023},
     month = sep,
     journal = {Carbon},
     volume = {213},
     pages = {118264},
     doi = {10.1016/j.carbon.2023.118264},
   }

2022

1. IJHMT

   

   Transition from Incoherent to Coherent Phonon Thermal Transport across Graphene/h-BN van Der Waals Superlattices

   Xin Wu, and Qiang Han^*

   International Journal of Heat and Mass Transfer, Mar 2022

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   The van der Waals (vdW) superlattice, obtained by applying the concept of the periodic superlattice to two-dimensional materials using low-energy vdW physical assembly, is undoubtedly an instrumental avenue for the modulation of material properties. In the field of nanoscale thermal transport, the influence of the periodic structure of superlattice on the wave-particle phonon transport regime arouses substantial interests from the standpoint of basic physics and applied science. In the Graphene/h-BN vdW superlattice, we have found the wave-particle crossover of phonon transport, which is reflected in the transition from incoherent to coherent regime as the interface density increases. The analysis reveals that the increased thermal conductivity owing to coherent transport effects will amply compensate for the progressively increasing interface phonon scattering throughout this process. In addition, due to the stronger effects of the above two aspects, the superlattices with higher interface density are more sensitive to changes in temperature and interface coupling strength, which are manifested in the rate of change in thermal conductivity caused by their alteration, respectively. These results establish an in-depth understanding of coherent phonon transport while exploring the possibility of phonon wave-particle crossover in vdW superlattices, providing guidance for related thermal management based on phonon engineering.

   @article{Wu_2022_Transition,
     title = {Transition from Incoherent to Coherent Phonon Thermal Transport across Graphene/h-BN van Der Waals Superlattices},
     author = {Wu, Xin and Han, Qiang},
     year = {2022},
     month = mar,
     journal = {International Journal of Heat and Mass Transfer},
     volume = {184},
     pages = {122390},
     doi = {10.1016/j.ijheatmasstransfer.2021.122390},
   }

2. IJHMT

   

   Maximum Thermal Conductivity of Multilayer Graphene with Periodic Two-Dimensional Empty Space

   Xin Wu, and Qiang Han^*

   International Journal of Heat and Mass Transfer, Aug 2022

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   With the ongoing development and maturation of van der Waals integration technology in recent years, the two-dimensional empty space (2D-ES) in multilayer graphene are undergoing a major breakthrough from conceptual realization to controlled design, which will open up novel possibilities in the micro-nano technology, including thermal transport. Herein, anomalous maximum in the in-plane thermal conductivity has been found by extensive molecular dynamics simulations in multilayer graphene with periodic 2D-ES. Analysis of the decomposition of the in-plane and out-of-plane contributions, which is of interest in laminated quasi-2D structures, shows that the out-of-plane part dominated by the influence of the vibrational modes, combined with the in-plane part under the influence of the compensation effect between the boundary scattering and the cavity barriers, together contribute to the thermal conductivity anomalous maximum. From property exploration to in-depth phonon analysis, a deep understanding of the phonon thermal transport behavior of multilayer graphene with periodic 2D-ES has been established, which is expected to further advance its application in the field of thermal management and design of nanomaterials.

   @article{Wu_2022_Maximum,
     title = {Maximum Thermal Conductivity of Multilayer Graphene with Periodic Two-Dimensional Empty Space},
     author = {Wu, Xin and Han, Qiang},
     year = {2022},
     month = aug,
     journal = {International Journal of Heat and Mass Transfer},
     volume = {191},
     pages = {122829},
     doi = {10.1016/j.ijheatmasstransfer.2022.122829},
   }

3. Sur.Interface

   

   Tunable Anisotropic In-Plane Thermal Transport of Multilayer Graphene Induced by 2D Empty Space: Insights from Interfaces

   Xin Wu, and Qiang Han^*

   Surfaces and Interfaces, Oct 2022

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   The emergence of two-dimensional empty space (2D-ES) not only enriches the means of van der Waals integration, but also provides a new and reliable solution for structural design-driven performance modulation. Here, by applying the concept of 2D-ES-based periodic structure design to multilayer graphene, the large-range tunable in-plane anisotropic phonon thermal transport behavior was discovered by extensive molecular dynamics simulations. Through a series of in-depth frequency-dependent and in-and-out of plane decomposition phonon analysis, it is found that 2D-ES and its interfaces with different periodic properties exhibit exactly opposite effects on phonon thermal transport along two in-plane orientations, which is the fundamental reason for the existence of the above-mentioned anisotropic thermal transport and its modulation. These findings provide new insights into the realization of in-plane anisotropic thermal transport in quasi-2D materials, which may further inspire novel thermal management strategies.

   @article{Wu_2022_Tunable,
     title = {Tunable Anisotropic In-Plane Thermal Transport of Multilayer Graphene Induced by 2D Empty Space: Insights from Interfaces},
     author = {Wu, Xin and Han, Qiang},
     year = {2022},
     month = oct,
     journal = {Surfaces and Interfaces},
     volume = {33},
     pages = {102296},
     doi = {10.1016/j.surfin.2022.102296},
   }

2021

1. ACS AMI

   

   Phonon Thermal Transport across Multilayer Graphene/Hexagonal Boron Nitride van Der Waals Heterostructures

   Xin Wu, and Qiang Han^*

   ACS Applied Materials & Interfaces, Jul 2021

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   Van der Waals (vdW) heterostructures stacked vertically by graphene (Gr) and hexagonal boron nitride (h-BN), by virtue of their novel properties, will undoubtedly spark great interests from the perspective of basic physics and applied science. Herein, phonon thermal transport across multilayer Gr/h-BN vdW heterostructures was systematically investigated by extensive molecular dynamics simulations, both in terms of internal structural configuration and external modulation. The former includes the structural configuration at the Gr/h-BN interface, the proportion of components in the effective heat transfer area, and size effect, while the latter includes cross-plane strain, temperature, and interfacial coupling strength. Our results show that at 300 K it has an ultralow out-of-plane thermal conductivity of only about 8.93 MW/m/K, while the Gr/h-BN interfacial thermal conductance (ITC) is up to about 300 MW/m2/K, and the latter can be modulated in a wide range from 0.5 to 3.5 times under cross-plane strain. The analysis of the spectral decomposition results indicates that the thermal transport across the Gr/h-BN interface depends almost entirely on low-frequency out-of-plane phonons below 10 THz and the quantum effect can be ignorable, which uncovers the physical mechanisms underlying the changes in the ITC and also points the path toward its modulation.

   @article{Wu_2021_Phonon,
     title = {Phonon Thermal Transport across Multilayer Graphene/Hexagonal Boron Nitride van Der Waals Heterostructures},
     author = {Wu, Xin and Han, Qiang},
     year = {2021},
     month = jul,
     journal = {ACS Applied Materials \& Interfaces},
     volume = {13},
     number = {27},
     pages = {32564--32578},
     doi = {10.1021/acsami.1c08275},
   }

2. JPCC

   

   Semidefective Graphene/h-BN In-Plane Heterostructures: Enhancing Interface Thermal Conductance by Topological Defects

   Xin Wu, and Qiang Han^*

   The Journal of Physical Chemistry C, Jan 2021

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   Two-dimensional (2D) in-plane heterostructures, whose interface thermal conductance (ITC) plays a crucial role in the thermal performance of nanostructured materials, will undoubtedly become the focus of the next-generation nanoelectronic devices. In this work, the semidefective graphene/hexagonal boron nitride in-plane heterostructures were innovatively proposed based on topological defects, and the thermal conductance across its interface was studied by molecular dynamics simulations. Surprisingly, the topological defects of a certain component in the heterostructure can significantly improve its ITC without changing the interfacial structure, and it is expected to be controlled by the defective concentration and the average temperature of the system. In particular, based on the different defective objects, the improvement of the ITC exhibits a radically different trend as the defective concentration increases. After the phonon activities were captured to explore the underlying physical mechanisms, it is found that the phonon coupling on both sides of the interface and the phonon localization effect of the heterostructure are two pivotal factors that determine the ITC of the heterostructure. The discovery of these results suggests a new path forward for improving or even controlling the ITC of the 2D in-plane heterostructures.

   @article{Wu_2021_Semidefective,
     title = {Semidefective Graphene/h-BN In-Plane Heterostructures: Enhancing Interface Thermal Conductance by Topological Defects},
     author = {Wu, Xin and Han, Qiang},
     year = {2021},
     month = jan,
     journal = {The Journal of Physical Chemistry C},
     volume = {125},
     number = {4},
     pages = {2748--2760},
     doi = {10.1021/acs.jpcc.0c10387},
   }

3. IJHMT

   

   Thermal Transport in Pristine and Defective Two-Dimensional Polyaniline (C3N)

   Xin Wu, and Qiang Han^*

   International Journal of Heat and Mass Transfer, Jul 2021

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   Two-dimensional polyaniline (2D-PANI) with semiconductor properties, a single crystalline carbon nitride with a stoichiometry of has attracted a lot of interest after its successful synthesis. In this study, the thermal transport properties in pristine and defective 2D-PANI were explored by extensive molecular dynamics (MD) simulations. Results based on three different versions of the MD method consistently showed that the lattice thermal conductivity of the pristine 2D-PANI is up to around . It decreases significantly after the introduction of structural defects and is essentially in a low-power law with the defects concentration. In addition, the difference in the weakening of thermal conductivity between vacancy and topological defects stems mainly from their respective differential effects on the low-frequency out-of-plane phonons. Remarkably, it also reveals the potential mutual constraints between anharmonic phonon-phonon scattering and phonon-defect scattering. These findings provide guidance for the thermal management of 2D-PANI-based electronic devices and are also expected to advance their application in the field of thermal design of nanomaterials.

   @article{Wu_2021_Thermal,
     title = {Thermal Transport in Pristine and Defective Two-Dimensional Polyaniline (C3N)},
     author = {Wu, Xin and Han, Qiang},
     year = {2021},
     month = jul,
     journal = {International Journal of Heat and Mass Transfer},
     volume = {173},
     pages = {121235},
     doi = {10.1016/j.ijheatmasstransfer.2021.121235},
   }

4. JAP

   

   Acoustic topological valley transport with multimode edge states

   Tianchong Wu, Xu Jiang, Xin Wu, and Qiang Han^*

   Journal of Applied Physics, Sep 2021

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   Acoustic transport through topological edge states in phononic crystals improves the suppression of backscattering, which gives these systems significant potential for controlling sound waves. Recent research shows that only one acoustic edge state caused by topological valley phases can transmit in phononic crystals. This paper proposes a genre of valley phases with one, two, and three topological edge states created by transforming the structure of unit cells. The bulk-edge correspondence indicates that these edge states are topological based on the topological invariant number (i.e., the valley Chern number of one, two, and three) of this system coinciding with the number of topological edge states. Different types of defects are introduced into the phononic crystals, whose transmission spectra show that they can withstand bending defects. These results indicate that these systems have significant potential for application in noise control, acoustic communication, and acoustic-electrical integration.

   @article{10.1063/5.0058715,
     author = {Wu, Tianchong and Jiang, Xu and Wu, Xin and Han, Qiang},
     title = {Acoustic topological valley transport with multimode edge states},
     journal = {Journal of Applied Physics},
     volume = {130},
     number = {12},
     pages = {124401},
     year = {2021},
     month = sep,
     issn = {0021-8979},
     doi = {10.1063/5.0058715},
     url = {https://doi.org/10.1063/5.0058715},
     eprint = {https://pubs.aip.org/aip/jap/article-pdf/doi/10.1063/5.0058715/13252743/124401\_1\_online.pdf}
   }

2020

1. Nanotech.

   

   Thermal Conductivity of Defective Graphene: An Efficient Molecular Dynamics Study Based on Graphics Processing Units

   Xin Wu, and Qiang Han^*

   Nanotechnology, Mar 2020

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   The exceptional thermal transport properties of graphene are affected due to the presence of various topological defects, which include single vacancy, double vacancies and Stone–Wales defects. The present article is intended to study on thermal transport properties of defective graphene by comparing the effects of topological defects on the thermal conductivity of graphene. This study developed a program for constructing defective graphene models with customizable defect concentrations and distribution types. The efficient molecular dynamics method based on graphics processing units is applied, which can achieve efficient and accurate calculation of material thermal conductivity. It is revealed that the existence of topological defects has a considerable reduce on the thermal conductivity of graphene, and the declining rate of the value get less with increasing defects concentration. At the same concentration, the weakening effect of SW defects on the thermal conductivity of graphene is evidently less than the other two defects. We also explored the effect of temperature on the thermal conductivity of graphene with different defects. These findings were discussed from the phonon perspective that elucidate the atomic level mechanisms, which provide guidance for thermal management of graphene devices.

   @article{Wu_2020_Thermala,
     title = {Thermal Conductivity of Defective Graphene: An Efficient Molecular Dynamics Study Based on Graphics Processing Units},
     author = {Wu, Xin and Han, Qiang},
     year = {2020},
     month = mar,
     journal = {Nanotechnology},
     volume = {31},
     number = {21},
     pages = {215708},
     doi = {10.1088/1361-6528/ab73bc},
   }

2. CMS

   

   Thermal Conductivity of Monolayer Hexagonal Boron Nitride: From Defective to Amorphous

   Xin Wu, and Qiang Han^*

   Computational Materials Science, Mar 2020

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   Through extensive molecular dynamics simulations, we completed the thermal transport properties study of the monolayer hexagonal boron nitride (h-BN) films from the defect state to the amorphous state. To this end, a defective h-BN model construction program has been developed, which can customize the nature of the defects and realize the transition from the defect state to the amorphous state. By performing homogeneous non-equilibrium molecular dynamics simulations based on Tersoff multi-body potential, the thermal conductivity results of large-size h-BN films have been achieved. For the defect state h-BN, we studied the effect of different defect types and concentrations on its thermal conductivity and verified it from the phonon mechanism. After the transition to two-dimensional amorphous BN, we discussed and analyzed the influence of amorphous concentration, amorphous defect ratio and temperature on its thermal transport properties. On this basis, the restriction relationship between phonon-phonon scattering term and phonon-defect scattering term was also proposed from the atomic level mechanisms. Our results constitute a step in the deterministic engineering of thermal management devices in 2D materials, and hold great promise for the application of h-BN defect engineering in the field of nanomaterial thermal design.

   @article{Wu_2020_Thermal,
     title = {Thermal Conductivity of Monolayer Hexagonal Boron Nitride: From Defective to Amorphous},
     author = {Wu, Xin and Han, Qiang},
     year = {2020},
     journal = {Computational Materials Science},
     volume = {184},
     pages = {109938},
     doi = {10.1016/j.commatsci.2020.109938},
   }

3. AMM

   

   Analysis of wave propagation in functionally graded piezoelectric composite plates reinforced with graphene platelets

   Chunlei Li, Qiang Han^*, Zhan Wang, and Xin Wu

   Applied Mathematical Modelling, May 2020

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   This paper presents a semi-analytical approach to investigate wave propagation characteristics in functionally graded graphene reinforced piezoelectric composite plates. Three patterns of graphene platelets (GPLs) describe the layer-wise variation of material properties in the thickness direction. Based on the Reissner-Mindlin plate theory and the isogeometric analysis, elastodynamic wave equation for the piezoelectric composite plate is derived by Hamilton’s principle and parameterized with the non-uniform rational B-splines (NURBS). The equation is transformed into a second-order polynomial eigenvalue problem with regard to wave dispersion. Then, the semi-analytical approach is validated by comparing with the existing results and the convergence on computing dispersion behaviors is also demonstrated. The effects of various distributions, volume fraction, size parameters and piezoelectricity of GPLs as well as different geometry parameters of the composite plate on dispersion characteristics are discussed in detail. The results show great potential of graphene reinforcements in design of smart composite structures and application for structural health monitoring.

   @article{LI2020487,
     title = {Analysis of wave propagation in functionally graded piezoelectric composite plates reinforced with graphene platelets},
     journal = {Applied Mathematical Modelling},
     volume = {81},
     pages = {487-505},
     year = {2020},
     month = may,
     issn = {0307-904X},
     doi = {https://doi.org/10.1016/j.apm.2020.01.016},
     author = {Li, Chunlei and Han, Qiang and Wang, Zhan and Wu, Xin}
   }

2019

1. J.Nanomater.

   

   Directional Gradientless Thermoexcited Rotating System Based on Carbon Nanotubes and Graphene

   Xin Wu, and Qiang Han^*

   Journal of Nanomaterials, May 2019

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   The simple and practicable intrinsic driving mechanism is of great significance for the design and development of nanoscale devices. This paper proposes a nanosystem that can achieve directional gradientless thermoexcited rotation at a relatively high temperature field (such as 300 K). In the case of a constant temperature field, the difference in atomic van der Waals (VDW) potentials in different regions of the rotor can be achieved by an asymmetric design of the structure, which provides torque for the rotation of the rotor. We studied the rotation and driving mechanism of the designed system through molecular dynamics (MD) simulation and discussed the influence of the chiral combination of carbon nanotubes, the chirality of graphene substrate, the length of graphene substrate, and the system temperature on rotation. At the same time, this paper also makes a qualitative analysis of the feasibility of the designed system from the perspective of molecular mechanics combined with energy. This research provides a new idea of nanoscale driving rotation, which has guiding significance for the design and application of related nanodevices in the future.

   @article{Wu_2019_Directional,
     title = {Directional Gradientless Thermoexcited Rotating System Based on Carbon Nanotubes and Graphene},
     author = {Wu, Xin and Han, Qiang},
     year = {2019},
     journal = {Journal of Nanomaterials},
     volume = {2019},
     pages = {1--9},
     doi = {10.1155/2019/8263843},
   }