LFOCKACE: Difference between revisions

Revision as of 17:52, 30 March 2023

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.^[1]

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

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. ^[1]) if you use this feature. The feature is used by default, if the Davidson algorithm (ALGO = Normal) is used; it is not used if ALGO = Damped or ALGO = All is set.

References

↑ ^a ^b L. Lin, J. Chem. Theory Comput. 12, 2242-2249 (2016).

[linlin:jctc:2016-1] L. Lin, J. Chem. Theory Comput. 12, 2242-2249 (2016).

[1]

@@ Line 10: / Line 10: @@
 For {{TAG|LFOCKACE}}=.FALSE. the conventional orbital representation is used.
-Note: it is good scientific practice to cite the original publication (Ref. {{cite|linlin:jctc:2016}}), if you use this feature. The feature is used by default, if the Davidson algorithm ({{TAG|ALGO}} = Normal) is used.
+Note: it is good scientific practice to cite the original publication (Ref. {{cite|linlin:jctc:2016}}) if you use this feature. The feature is used by default, if the Davidson algorithm ({{TAG|ALGO}} = Normal) is used; it is not used if {{TAG|ALGO}} = Damped or {{TAG|ALGO}} = All is set.
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