NBANDSEXACT

NBANDSEXACT = [integer]

Default: NBANDSEXACT	= -1	for LALL_IN_ONE=.FALSE.
	= maximum number of plane waves	for LALL_IN_ONE=.TRUE.

Description: NBANDSEXACT specifies the number of bands used in the all-in-one mode of many-body perturbation theory calculations.

Mind: available as of VASP.6.4.0

In the all-in-one mode, VASP automatically performs the necessary DFT steps prior to the many-body perturbation theory (MBPT) calculation, i.e. a DFT calculation with NBANDS, followed by an exact diagonalization of the Kohn-Sham Hamiltonian with NBANDSEXACT bands. Note, NBANDSEXACT is set by default to the maximum number of plane-waves given by the chosen energy cutoff for the orbitals ENCUT. In the all-in-one mode, the actual GW/RPA calculation is also performed with NBANDSEXACT bands. If NBANDS_WAVE is not set, all orbitals are written to WAVECAR, which potentially becomes huge in file size.

Tip: The NBANDS_WAVE tag can be used to limit the number of bands written to WAVECAR if LALL_IN_ONE=.TRUE.

The all-in-one mode is automatically enabled for ALGO=[EV]GW[0]R, RPA[R],ACFDT[R] if NBANDS is not set.

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