The redistribution of charge (spin) density induced by the interaction between
two systems A and B can be analyzed by the following procedure:
(i) Calculate the composite system consisting of A and B
Then, you will have a cube file for charge (spin) density. Let it be 'AB.cube'.
Also, you will find 'Grid_Origin' in the standard output which gives -, -,
and -components of the origin of the regular grid as:
Grid_Origin xxx yyy zzzThe values will be used in the following calculations (ii) and (iii).
scf.fixed.grid xxx yyy zzzwhere 'xxx yyy zzz' is the coordinate of the origin you got in the calculation (i). Then, you will have a cube file for charge (spin) density. Let it be 'A.cube'.
scf.fixed.grid xxx yyy zzzwhere 'xxx yyy zzz' is the coordinate of the origin you got in the calculation (i). Then, you will have a cube file for charge (spin) density. Let it be 'B.cube'.
% gcc diff_gcube.c -lm -o diff_gcube % gcc add_gcube.c -lm -o add_gcube(v) Generate a cube file for difference charge (spin) density
% ./add_gcube A.cube B.cube A_B.cubeThe file 'A_B.cube' is the cube file for the superposition of charge (spin) density of two isolated systems. Then, you can generate a cube file for the difference charge (spin) density induced by the interaction as follows:
% ./diff_gcube AB.cube A_B.cube dAB.cubeThe file 'dAB.cube' is the cube file for the difference charge (spin) density induced by the interaction, where the difference means (AB - A_B).