LFOCKACE: Difference between revisions
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Description: {{TAG|LFOCKACE}} determines whether the Adaptively Compressed Exchange Operator is used.{{cite|linlin:jctc:2016}} | Description: {{TAG|LFOCKACE}} determines whether the Adaptively Compressed Exchange Operator is used.{{cite|linlin:jctc:2016}} | ||
*N.B.:Available for CPU and OpenACC version of VASP.6 when compiled with [[Precompiler flags|- | *N.B.:Available for CPU and OpenACC version of VASP.6 when compiled with [[Precompiler flags|-Dfock_dblbuf]]. | ||
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For {{TAGBL|LFOCKACE}}=.TRUE. the Cholesky decomposition <math>X=LL^\dagger</math> of the Fock exchange matrix <math>X_{ij} = \langle \tilde\psi_i \mid \tilde V_X \mid \tilde\psi_j \rangle </math> is calculated and the adaptively compressed exchange operator <math>\tilde V_{ACE} = -\sum_i \mid \tilde X_i \rangle \langle \tilde X_i \mid </math> is used for the action of the Fock exchange on the pseudo orbitals. This method can be used for [[Hartree-Fock_and_HF/DFT_hybrid_functionals|hybrid functionals]] in combination with the Davidson algorithm ({{TAGBL|ALGO}}=Normal) to save a factor of <math>\approx 3</math> in computation time. | For {{TAGBL|LFOCKACE}}=.TRUE. the Cholesky decomposition <math>X=LL^\dagger</math> of the Fock exchange matrix <math>X_{ij} = \langle \tilde\psi_i \mid \tilde V_X \mid \tilde\psi_j \rangle </math> is calculated and the adaptively compressed exchange operator <math>\tilde V_{ACE} = -\sum_i \mid \tilde X_i \rangle \langle \tilde X_i \mid </math> is used for the action of the Fock exchange on the pseudo orbitals. This method can be used for [[Hartree-Fock_and_HF/DFT_hybrid_functionals|hybrid functionals]] in combination with the Davidson algorithm ({{TAGBL|ALGO}}=Normal) to save a factor of <math>\approx 3</math> in computation time. | ||
Revision as of 14:04, 16 December 2019
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 of the Fock exchange matrix is calculated and the adaptively compressed exchange operator 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 in computation time.
For LFOCKACE=.TRUE. the conventional orbital representation is used.
Related Tags and Sections
AEXX, AEXX, AGGAX, AGGAC, LHFCALC, hybrid functionals, settings for specific hybrid functionals