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; ACS is not used for ALGO = Damped or ALGO = All.

Related tags and articles

AEXX, AEXX, AGGAX, AGGAC, LHFCALC, settings for specific hybrid functionals

Examples that use this tag

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