LMAXFOCKAE: Difference between revisions
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Usually VASP restores only the ''moments'' of the all-electron charge density on the plane wave grid (see {{TAG|LMAXFOCK}}) up to a certain ''l'' quantum number. It is, however, also possible to restore the ''shape'' of the charge density accurately on the plane wave grid, using the flag {{TAG|LMAXFOCKAE}}. | Usually VASP restores only the ''moments'' of the all-electron charge density on the plane wave grid (see {{TAG|LMAXFOCK}}) up to a certain ''l'' quantum number. It is, however, also possible to restore the ''shape'' of the charge density accurately on the plane wave grid, using the flag {{TAG|LMAXFOCKAE}}. | ||
If {{TAG|LMAXFOCKAE}} is set, the shape of the charge density is restored accurately on the plane wave grid up to a typical plane wave energy of 100 eV. (Beyond that cutoff the polarizability is usually very small (<0.01), necessitating no accurate treatment.) | |||
This flag usually hardly changes the total energy or one-electron states, since the one-center-terms are calculated exactly for most Hamiltonians (the one-center terms are defined as the difference between the pseudized one-center terms and the all-electron one-center terms). However for the following type of Hamiltonians, one-center terms are currently not implemented, or only approximately implemented: | This flag usually hardly changes the total energy or one-electron states, since the one-center-terms are calculated exactly for most Hamiltonians (the one-center terms are defined as the difference between the pseudized one-center terms and the all-electron one-center terms). However for the following type of Hamiltonians, one-center terms are currently not implemented, or only approximately implemented: | ||
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In these cases, it is recommended to set {{TAG|LMAXFOCKAE}} to twice the maximum ''l'' quantum number found in the {{FILE|POTCAR}} file. | In these cases, it is recommended to set {{TAG|LMAXFOCKAE}} to twice the maximum ''l'' quantum number found in the {{FILE|POTCAR}} file. | ||
For ''GW'' calculations involving | For ''GW'' calculations involving first row elements set {{TAG|LMAXFOCKAE}} = 2. For ''GW'' calculations involving transition metals {{TAG|LMAXFOCKAE}} = 4 is recommended. | ||
== Related Tags and Sections == | == Related Tags and Sections == | ||
Revision as of 11:12, 7 March 2011
LMAXFOCKAE = [integer]
Default: LMAXFOCKAE = -1
Description: LMAXFOCKAE sets the maximum angular momentum quantum number l for the "accurate" augmentation of charge densities in Hartree-Fock type routines.
Usually VASP restores only the moments of the all-electron charge density on the plane wave grid (see LMAXFOCK) up to a certain l quantum number. It is, however, also possible to restore the shape of the charge density accurately on the plane wave grid, using the flag LMAXFOCKAE.
If LMAXFOCKAE is set, the shape of the charge density is restored accurately on the plane wave grid up to a typical plane wave energy of 100 eV. (Beyond that cutoff the polarizability is usually very small (<0.01), necessitating no accurate treatment.)
This flag usually hardly changes the total energy or one-electron states, since the one-center-terms are calculated exactly for most Hamiltonians (the one-center terms are defined as the difference between the pseudized one-center terms and the all-electron one-center terms). However for the following type of Hamiltonians, one-center terms are currently not implemented, or only approximately implemented:
- Thomas-Fermi type screening (LTHOMAS=.TRUE.)
- GW calculations
In these cases, it is recommended to set LMAXFOCKAE to twice the maximum l quantum number found in the POTCAR file.
For GW calculations involving first row elements set LMAXFOCKAE = 2. For GW calculations involving transition metals LMAXFOCKAE = 4 is recommended.