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Improvement of initial guess via grid‐cutting for efficient grid‐based density functional calculations
Author(s) -
Lim Jaechang,
Choi Sunghwan,
Kang Sungwoo,
Kim Jaewook,
Hong Kwangwoo,
Kim Woo Youn
Publication year - 2016
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.25193
Subject(s) - superposition principle , atomic orbital , density functional theory , grid , linear combination of atomic orbitals , basis set , molecular orbital , statistical physics , chemistry , molecular physics , molecule , atomic physics , computational physics , computational chemistry , physics , quantum mechanics , mathematics , geometry , electron
We introduced an efficient initial guess method, namely the grid‐cutting, which is specialized for grid‐based density functional theory (DFT) calculations. It produces initial density and orbitals through pre‐DFT calculations in an inner simulation box made by cutting out the outer region of a full‐size one. To assess its performance, we carried out DFT calculations for small molecules included in the G2‐1 set and two large molecules with various combinations of mixing and diagonalization conditions, relative size of the inner box, and grid spacing. For all cases, the grid‐cutting method was more efficient than conventional ones such as extended Hückel, superposition of atomic densities, and linear combination of atomic orbitals. For instance, it was about 20% faster in computational time and about 45% smaller in the number of self‐consistent‐field cycles than the superposition of atomic densities because it provided high‐quality initial density and orbitals closer to the corresponding fully converged values. In addition, it showed good performance for non‐Coulombic model systems such as harmonic oscillator.