luanzhanglei123的个人博客分享 http://blog.sciencenet.cn/u/luanzhanglei123

博文

VASP计算时设置LAECHG=T的官方说明

已有 5248 次阅读 2019-9-18 14:38 |个人分类:科学研究|系统分类:科研笔记

VASP计算时设置LAECHG=.TRUE.进行的所谓的全电子计算,常用的地方是Bader charge分析,官方说明如下:

LAECHG = .TRUE. | .FALSE.
Default: LAECHG = .FALSE. 

Description: when LAECHG=.TRUE. the all-electron charge density will be reconstructed explicitly and written out to file.

If LAECHG=.TRUE. is set VASP will reconstruct the all-electron charge density on the so-called "fine" FFT-grid. This "fine" FFT-grid consists of NGXF×NGYF×NGZF points in real space (i.e., the grid that is used to represent the augmented pseudo charge densities of the USPP and PAW methods).

In fact, for LAECHG=.TRUE., VASP will reconstruct three distinct all-electron densities:

the core density.

the proto-atomic valence density (overlapping atomic charge densities).

the self-consistent valence density.

These are written to the files AECCAR0, AECCAR1, and AECCAR2, respectively. The first two of these files are written at the start of the run, whereas the last is written at the end after self-consistency has been reached.

N.B.: In the language of the PAW method an "all-electron" density does not refer to the density of all electrons, instead it denotes a density that includes all the nodal features near the nucleus associated with the true (as opposed to the pseudized) one-electron orbitals. Within the PAW method, the all-electron density arising from the one-electron pseudo orbitals  is given by:

Normally one does not attempt to reconstruct all-electron densities explicitly since the second term on the right hand side varies rapidly near the nuclei and is too costly to expand in plane waves (see the bit about augmentation and compensation charges). For LAECHG=.TRUE., however, this reconstruction is exactly the thing that is done.




https://blog.sciencenet.cn/blog-2827406-1198494.html

上一篇:VASP计算添加Empty spheres时的注意事项
下一篇:VASP报错记录20190920
收藏 IP: 220.166.33.*| 热度|

0

该博文允许注册用户评论 请点击登录 评论 (1 个评论)

数据加载中...

Archiver|手机版|科学网 ( 京ICP备07017567号-12 )

GMT+8, 2024-3-28 22:34

Powered by ScienceNet.cn

Copyright © 2007- 中国科学报社

返回顶部