ELPH WF CACHE MB - Revision history

Huebsch: Huebsch moved page Construction:ELPH WF CACHE MB to ELPH WF CACHE MB without leaving a redirect

2026-06-18T13:57:06Z

Huebsch moved page Construction:ELPH WF CACHE MB to ELPH WF CACHE MB without leaving a redirect

← Older revision		Revision as of 13:57, 18 June 2026
(No difference)

Csheldon at 13:56, 18 June 2026

2026-06-18T13:56:57Z

← Older revision		Revision as of 13:56, 18 June 2026
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	Electron-phonon matrix elements are sandwiches of the form		Electron-phonon matrix elements are sandwiches of the form
	:<math>\langle \psi_{n\mathbf{k}} \| \Delta V_{\mathbf{q}} \| \psi_{m\mathbf{k}'} \rangle,</math>		:<math>\langle \psi_{n\mathbf{k}} \| \Delta V_{\mathbf{q}} \| \psi_{m\mathbf{k}'} \rangle,</math>
	where <math>\mathbf{k}' = \mathbf{k} + \mathbf{q}</math>. Because k-points are distributed across MPI ranks, the wavefunction <math>\psi_{n\mathbf{k}}</math> needed to form the bra may reside on a different rank than the one computing the matrix element. ~~<code>~~ELPH_WF_CACHE_MB~~</code>~~ sets the maximum memory (in megabytes) used to cache these remotely fetched wavefunctions locally, avoiding repeated inter-rank MPI communication.		where <math>\mathbf{k}' = \mathbf{k} + \mathbf{q}</math>. Because k-points are distributed across MPI ranks, the wavefunction <math>\psi_{n\mathbf{k}}</math> needed to form the bra may reside on a different rank than the one computing the matrix element. {{TAG\|ELPH_WF_CACHE_MB}} sets the maximum memory (in megabytes) used to cache these remotely fetched wavefunctions locally, avoiding repeated inter-rank MPI communication.

	A separate cache for the PAW projections is also sized proportionally to ~~<code>~~ELPH_WF_CACHE_MB~~</code>~~.		A separate cache for the PAW projections is also sized proportionally to {{TAG\|ELPH_WF_CACHE_MB}}.

	The wavefunction cache works together with {{TAG\|ELPH_WF_CACHE_PREFILL}} (default: <code>.TRUE.</code>), which pre-populates the cache before the main electron-phonon loop begins. When pre-fill succeeds, almost all subsequent wavefunction accesses are served from the cache without MPI communication.		The wavefunction cache works together with {{TAG\|ELPH_WF_CACHE_PREFILL}} (default: <code>.TRUE.</code>), which pre-populates the cache before the main electron-phonon loop begins. When pre-fill succeeds, almost all subsequent wavefunction accesses are served from the cache without MPI communication.

Csheldon at 13:34, 18 June 2026

2026-06-18T13:34:49Z

← Older revision		Revision as of 13:34, 18 June 2026
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	{{DISPLAYTITLE\|ELPH_WF_CACHE_MB}}		{{DISPLAYTITLE:ELPH_WF_CACHE_MB}}
	{{TAGDEF\|ELPH_WF_CACHE_MB\|real\|1000}}		{{TAGDEF\|ELPH_WF_CACHE_MB\|real\|1000}}

Miranda.henrique: Update related tags: add ELPH_WF_CACHE_PREFILL, ELPH_WF_COMM_OPT, ELPH_WF_REDISTRIBUTE; remove ELPH_MELS, ELPH_NQBATCH, ELPH_NSIM

2026-06-18T12:28:54Z

Update related tags: add ELPH_WF_CACHE_PREFILL, ELPH_WF_COMM_OPT, ELPH_WF_REDISTRIBUTE; remove ELPH_MELS, ELPH_NQBATCH, ELPH_NSIM

← Older revision		Revision as of 12:28, 18 June 2026
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	==Related tags and articles==		==Related tags and articles==
	{{TAG\|~~ELPH_MELS~~}}, {{TAG\|~~ELPH_NQBATCH~~}}, {{TAG\|~~ELPH_NSIM~~}}, {{TAG\|ELPH_RUN}}		* {{TAG\|ELPH_WF_CACHE_PREFILL}}
			* {{TAG\|ELPH_WF_COMM_OPT}}
			* {{TAG\|ELPH_WF_REDISTRIBUTE}}
			* {{TAG\|ELPH_RUN}}

	[[Category:INCAR tag]][[Category:Electron-phonon interactions]]		[[Category:INCAR tag]][[Category:Electron-phonon interactions]]

Miranda.henrique: Use MathJax for matrix element formula; link ELPH_WF_CACHE_PREFILL

2026-06-18T12:27:10Z

Use MathJax for matrix element formula; link ELPH_WF_CACHE_PREFILL

← Older revision		Revision as of 12:27, 18 June 2026
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	Electron-phonon matrix elements are sandwiches of the form		Electron-phonon matrix elements are sandwiches of the form
	⟨ψ<~~sub~~>n~~'''~~k~~'''</sub>~~\|~~ΔV<sub>'''~~q~~'''</sub>~~\|~~ψ<sub>~~m~~'''~~k'~~''′~~</~~sub~~>⟩,		:<math>\langle \psi_{n\mathbf{k}} \| \Delta V_{\mathbf{q}} \| \psi_{m\mathbf{k}'} \rangle,</math>
	where ~~'''~~k'~~''′~~ = ~~'''~~k~~'''~~ + ~~'''~~q~~'''~~. Because k-points are distributed across MPI ranks, the wavefunction ψ<~~sub~~>n~~'''~~k~~'''~~</~~sub~~> needed to form the bra may reside on a different rank than the one computing the matrix element. <code>ELPH_WF_CACHE_MB</code> sets the maximum memory (in megabytes) used to cache these remotely fetched wavefunctions locally, avoiding repeated inter-rank MPI communication.		where <math>\mathbf{k}' = \mathbf{k} + \mathbf{q}</math>. Because k-points are distributed across MPI ranks, the wavefunction <math>\psi_{n\mathbf{k}}</math> needed to form the bra may reside on a different rank than the one computing the matrix element. <code>ELPH_WF_CACHE_MB</code> sets the maximum memory (in megabytes) used to cache these remotely fetched wavefunctions locally, avoiding repeated inter-rank MPI communication.

	A separate cache for the PAW projections is also sized proportionally to <code>ELPH_WF_CACHE_MB</code>.		A separate cache for the PAW projections is also sized proportionally to <code>ELPH_WF_CACHE_MB</code>.

	The wavefunction cache works together with ~~<code>~~ELPH_WF_CACHE_PREFILL~~</code>~~ (default: <code>.TRUE.</code>), which pre-populates the cache before the main electron-phonon loop begins. When pre-fill succeeds, almost all subsequent wavefunction accesses are served from the cache without MPI communication.		The wavefunction cache works together with {{TAG\|ELPH_WF_CACHE_PREFILL}} (default: <code>.TRUE.</code>), which pre-populates the cache before the main electron-phonon loop begins. When pre-fill succeeds, almost all subsequent wavefunction accesses are served from the cache without MPI communication.

	==Related tags and articles==		==Related tags and articles==

Miranda.henrique at 12:15, 18 June 2026

2026-06-18T12:15:46Z

← Older revision		Revision as of 12:15, 18 June 2026
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	Description: Maximum memory (in MB) allocated for caching wavefunctions during electron-phonon matrix element calculations.		Description: Maximum memory (in MB) allocated for caching wavefunctions during electron-phonon matrix element calculations.

	{{Available\|6.5.1}}		{{Available\|6.5.1}}
	----		----
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	A separate cache for the PAW projections is also sized proportionally to <code>ELPH_WF_CACHE_MB</code>.		A separate cache for the PAW projections is also sized proportionally to <code>ELPH_WF_CACHE_MB</code>.

	~~{{NB\|text=If the cache fills during the calculation, VASP aborts with the message <code>wf cache is full</code>. Increase <code>ELPH_WF_CACHE_MB</code> until the error no longer occurs.}}~~

	The wavefunction cache works together with <code>ELPH_WF_CACHE_PREFILL</code> (default: <code>.TRUE.</code>), which pre-populates the cache before the main electron-phonon loop begins. When pre-fill succeeds, almost all subsequent wavefunction accesses are served from the cache without MPI communication.		The wavefunction cache works together with <code>ELPH_WF_CACHE_PREFILL</code> (default: <code>.TRUE.</code>), which pre-populates the cache before the main electron-phonon loop begins. When pre-fill succeeds, almost all subsequent wavefunction accesses are served from the cache without MPI communication.

Miranda.henrique: Add ELPH_WF_CACHE_MB tag page: wavefunction cache for electron-phonon MPI communication

2026-06-18T12:14:06Z

Add ELPH_WF_CACHE_MB tag page: wavefunction cache for electron-phonon MPI communication

← Older revision	Revision as of 12:14, 18 June 2026
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		{{DISPLAYTITLE\|ELPH_WF_CACHE_MB}}
		{{TAGDEF\|ELPH_WF_CACHE_MB\|real\|1000}}

		Description: Maximum memory (in MB) allocated for caching wavefunctions during electron-phonon matrix element calculations.

		{{Available\|6.5.1}}
		----

		Electron-phonon matrix elements are sandwiches of the form
		⟨ψ<sub>n'''k'''</sub>\|ΔV<sub>'''q'''</sub>\|ψ<sub>m'''k'''′</sub>⟩,
		where '''k'''′ = '''k''' + '''q'''. Because k-points are distributed across MPI ranks, the wavefunction ψ<sub>n'''k'''</sub> needed to form the bra may reside on a different rank than the one computing the matrix element. <code>ELPH_WF_CACHE_MB</code> sets the maximum memory (in megabytes) used to cache these remotely fetched wavefunctions locally, avoiding repeated inter-rank MPI communication.

		A separate cache for the PAW projections is also sized proportionally to <code>ELPH_WF_CACHE_MB</code>.

		{{NB\|text=If the cache fills during the calculation, VASP aborts with the message <code>wf cache is full</code>. Increase <code>ELPH_WF_CACHE_MB</code> until the error no longer occurs.}}

		The wavefunction cache works together with <code>ELPH_WF_CACHE_PREFILL</code> (default: <code>.TRUE.</code>), which pre-populates the cache before the main electron-phonon loop begins. When pre-fill succeeds, almost all subsequent wavefunction accesses are served from the cache without MPI communication.

		==Related tags and articles==
		{{TAG\|ELPH_MELS}}, {{TAG\|ELPH_NQBATCH}}, {{TAG\|ELPH_NSIM}}, {{TAG\|ELPH_RUN}}

		[[Category:INCAR tag]][[Category:Electron-phonon interactions]]

Miranda.henrique: Created blank page

2026-06-18T12:12:04Z

Created blank page

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