Adaptive local basis set for Kohn-Sham density functional theory in a discontinuous Galerkin framework II: Force, vibration, and molecular dynamics calculations

JOURNAL OF COMPUTATIONAL PHYSICS

卷:335

Article

Zhang, Gaigong²  Lin, Lin^1,2  Hu, Wei²  Yang, Chao²  Pask, John E.³ 

[1] Univ Calif Berkeley, Dept Math, Berkeley, CA 94720 USA

[2] Lawrence Berkeley Natl Lab, Computat Res Div, Berkeley, CA 94720 USA

[3] Lawrence Livermore Natl Lab, Div Phys, Livermore, CA 94550 USA

关键词: Electronic structure;    Kohn-Sham density functional theory;    Discontinuous Galerkin;    Adaptive local basis set;    Hellmann-Feynman force;    Pulay force;    Molecular dynamics;   

DOI  :  10.1016/j.jcp.2016.12.052

来源: Elsevier

【 摘 要 】

Recently, we have proposed the adaptive local basis set for electronic structure calculations based on Kohn-Sham density functional theory in a pseudopotential framework. The adaptive local basis set is efficient and systematically improvable for total energy calculations. In this paper, we present the calculation of atomic forces, which can be used for a range of applications such as geometry optimization and molecular dynamics simulation. We demonstrate that, under mild assumptions, the computation of atomic forces can scale nearly linearly with the number of atoms in the system using the adaptive local basis set. We quantify the accuracy of the Hellmann-Feynman forces for a range of physical systems, benchmarked against converged planewave calculations, and find that the adaptive local basis set is efficient for both force and energy calculations, requiring at most a few tens of basis functions per atom to attain accuracies required in practice. Since the adaptive local basis set has implicit dependence on atomic positions, Pulay forces are in general nonzero. However, we find that the Pulay force is numerically small and systematically decreasing with increasing basis completeness, so that the HellmannFeynman force is sufficient for basis sizes of a few tens of basis functions per atom. We verify the accuracy of the computed forces in static calculations of quasi-1D and 3D disordered Si systems, vibration calculation of a quasi-1D Si system, and molecular dynamics calculations of H-2 and liquid Al-Si alloy systems, where we show systematic convergence to benchmark planewave results and results from the literature. (C) 2016 Elsevier Inc. All rights reserved.

【 授权许可】

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