PARCHG

PARCHG is an output file created when partial charge densities are calculated by setting LPARD = .TRUE.. The file has the same structure as the CHG file, containing the structure followed by the charge density on the fine FFT-grid, but missing the augmentation occupancies that are written to CHGCAR. The units are also equivalent to CHG and CHGCAR, charge density $n(r)$ multiplied by the grid volume $V_\mathrm{grid}$ = NGXF$\times$NGYF$\times$NGZF, $n(r)\times V_{\mathrm{grid}}$.

The density written to PARCHG is the valence electron density, that was converged selfconsistently in a previous run. The bands and k points that contribute to the partial charges are selected by the IBAND, NBMOD, EINT and KPUSE tags, allowing for fine control of the contributions to the partial charge density.

Spin-polarized calculation

In spin-polarized calculations, two sets of data are stored in the PARCHG file. The first set contains the total partial density (spin up + spin down) and the second one is the magnetization density (spin up - spin down). Each block is separated by a blank line and a line containing the fine FFT-grid dimensions NGXF NGYF NGZF.

• structure
• total charge density (spin up + spin down)
• magnetization density (spin up - spin down)

Variants of PARCHG with bands or k points separated

If LSEPB and/or LSEPK are set to .TRUE. variants of the PARCHG file are written, separating the contributing bands and k points respectively. The units and format of the files stay the same.

If LSEPB = .TRUE. but LSEPK = .FALSE. PARCHG.nb.ALLK files will be written, with nb an index running through all bands contributing to the partial charge density.

LSEPB = .FALSE. but LSEPK = .TRUE. results in PARCHG.ALLB.nk files being created, with nk running over all k points in KPUSE or all k points if KPUSE is not set.

For both LSEPB = .TRUE. and LSEPK = .TRUE. all combinations are written to PARCHG.nb.nk files.

Related tags and articles

LPARD, IBAND, EINT, NBMOD, KPUSE, LSEPB, LSEPK, Band decomposed charge densities

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