LFOCKACE

LFOCKACE = .TRUE. | .FALSE.
Default: LFOCKACE = .TRUE. 

Default: LFOCKACE	= .TRUE.	for VASP.6
	= N/A	for VASP.5.X and older

Description: LFOCKACE determines whether the Adaptively Compressed Exchange Operator is used.

• N.B.:Available for CPU and OpenACC version of VASP.6 when compiled with -Dfock_dblbuf.

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For LFOCKACE=.TRUE. the Cholesky decomposition $X=LL^{\dagger }$ of the Fock exchange matrix $X_{ij}=\langle {\tilde {\psi }}_{i}\mid {\tilde {V}}_{X}\mid {\tilde {\psi }}_{j}\rangle$ is calculated and the adaptively compressed exchange operator ${\tilde {V}}_{ACE}=-\sum _{i}\mid {\tilde {X}}_{i}\rangle \langle {\tilde {X}}_{i}\mid$ is used for the action of the Fock exchange on the pseudo orbitals. This method can be used for hybrid functionals in combination with the Davidson algorithm (ALGO=Normal) to save a factor of $\approx 3$ in computation time.

For LFOCKACE=.FALSE. the conventional orbital representation is used.

Note: it is good scientific practice to cite the original publication (Ref. ) if you use this feature. The feature is used by default, if the Davidson algorithm (ALGO = Normal) is used; ACE is not used for ALGO = Damped or ALGO = All.

Related tags and articles

AEXX, AEXX, AGGAX, AGGAC, LHFCALC, List of hybrid functionals, Hybrid functionals: formalism

Examples that use this tag

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