ELPH_WF_CACHE_PREFILL
ELPH_WF_CACHE_PREFILL = logical
Default: ELPH_WF_CACHE_PREFILL = .TRUE.
Description: Pre-fills the wavefunction cache before the main electron-phonon loop begins.
| Mind: Available as of VASP 6.5.0 |
When computing electron-phonon matrix elements, VASP caches wavefunctions fetched from remote MPI ranks (see ELPH_WF_CACHE_MB). With ELPH_WF_CACHE_PREFILL = .TRUE. (the default), all required wavefunctions are gathered into the cache in a single communication phase before the main loop starts. This means the loop itself runs with little or no inter-rank MPI traffic.
Setting ELPH_WF_CACHE_PREFILL = .FALSE. disables pre-filling; wavefunctions are then fetched on demand during the loop. This reduces the upfront communication cost but increases total MPI traffic and is generally slower.