Calculation of phonon dispersion relation using new correlation functional

International Conference on Aerospace, Mechanical and Mechatronic Engineering

航空航天工程;机械制造;无线电电子学

Jitropas, Ukrit^1 ; Hsu, Chung-Hao^1

School of Manufacturing Systems and Mechanical Engineering, Sirindhorn, International Institute of Technology, Thammasat University, Pathum Thani

12120, Thailand^1

关键词: Approximation approach;    Correlation functionals;    First-principle approach;    General expression;    Ground-state energies;    Phonon dispersion relations;    Quantum monte carlo;    Thermal properties of materials;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/211/1/012002/pdf
DOI  :  10.1088/1757-899X/211/1/012002

学科分类：航空航天科学

来源: IOP

【 摘 要 】

To extend the use of Local Density Approximation (LDA), a new analytical correlation functional is introduced. Correlation energy is an essential ingredient within density functional theory and used to determine ground state energy and other properties including phonon dispersion relation. Except for high and low density limit, the general expression of correlation energy is unknown. The approximation approach is therefore required. The accuracy of the modelling system depends on the quality of correlation energy approximation. Typical correlation functionals used in LDA such as Vosko-Wilk-Nusair (VWN) and Perdew-Wang (PW) were obtained from parameterizing the near-exact quantum Monte Carlo data of Ceperley and Alder. These functionals are presented in complex form and inconvenient to implement. Alternatively, the latest published formula of Chachiyo correlation functional provides a comparable result for those much more complicated functionals. In addition, it provides more predictive power based on the first principle approach, not fitting functionals. Nevertheless, the performance of Chachiyo formula for calculating phonon dispersion relation (a key to the thermal properties of materials) has not been tested yet. Here, the implementation of new correlation functional to calculate phonon dispersion relation is initiated. The accuracy and its validity will be explored.