Charge Density Difference

rsgrad chgdiff can calculate the charge density difference from CHGCAR files:

$$ \Delta \rho = \rho_{A+B} - (\rho_A + \rho_B) $$

Where \(\rho_{A+B}\), \(\rho_A\) and \(\rho_B\) are the charge densities of total structure, A structure and B structure, respectively.

You may also need rsgrad poscar --split ... to generate the structure of A and B from A+B.

Help message

$ rsgrad chgdiff --help
rsgrad-chgdiff
Calculate charge density difference.

The operation is performed by `chgdiff = chgcar_ab - (chgcar_a + chgcar_b)`.

USAGE:
    rsgrad chgdiff [OPTIONS] <CHGCAR_AB> <CHGCAR_A> <CHGCAR_B>

ARGS:
    <CHGCAR_AB>
            The CHGCAR of A+B system

    <CHGCAR_A>
            The CHGCAR of A system

    <CHGCAR_B>
            The CHGCAR of B system

OPTIONS:
    -h, --help
            Print help information

    -o, --output <OUTPUT>
            The output charge density difference file path

            [default: CHGDIFF.vasp]

Example

You need to calculate the electronic structure of the three structures (A+B, A and B) first, then rsgrad chgdiff CHGCAR_A+B CHGCAR_A CHGCAR_B like

$ rsgrad chgdiff ../scf/CHGCAR Ag/CHGCAR noAg/CHGCAR
[2022-07-14T18:34:59Z INFO  rsgrad::commands::chgdiff] Reading charge density from "Ag/CHGCAR"
[2022-07-14T18:34:59Z INFO  rsgrad::commands::chgdiff] Reading charge density from "noAg/CHGCAR"
[2022-07-14T18:34:59Z INFO  rsgrad::commands::chgdiff] Reading charge density from "../scf/CHGCAR"
[2022-07-14T18:35:06Z INFO  rsgrad::commands::chgdiff] Calculating charge density difference by `CHGDIFF = "../scf/CHGCAR" - ("Ag/CHGCAR" + "noAg/CHGCAR")`
[2022-07-14T18:35:06Z INFO  rsgrad::commands::chgdiff] Writing charge difference to "CHGDIFF.vasp"
[2022-07-14T18:35:10Z INFO  rsgrad] Time used: 11.189259653s

finally use VESTA to visualize the data