ALGO: Difference between revisions

Revision as of 15:47, 15 September 2017

Description: the ALGO tag is a convenient option to specify the electronic minimisation algorithm (as of VASP.4.5) and/or to select the type of GW calculations.

ALGO=Normal selects IALGO=38 (blocked Davidson iteration scheme).

ALGO=VeryFast selects IALGO=48 (RMM-DIIS).

ALGO=Fast selects a faily robust mixture of the Davidson and RMM-DIIS algorithms. In this case, Davidson (IALGO=38) is used for the initial phase, and then VASP switches to RMM-DIIS (IALGO=48). Subsequencly, for each ionic update, one IALGO=38 sweep is performed for each ionic step (except the first one).

ALGO=Conjugate or ALGO=All selects an "all band simultaneous update of orbitals" (IALGO=58, in both cases the same conjugate gradient algorithm is used).

ALGO=Damped selects a damped velocity friction algorithm (IALGO=53).

ALGO=Subrot selects subspace rotation or diagonalization in the sub-space spanned by the orbitals (IALGO=4).

ALGO=Eigenval allows to recalculate one electron energies, density of state and perform selected postprocessing using the current orbitals (IALGO=3) e.g. read from the WAVECAR file.

ALGO=None or ALGO=Nothing allows to recalculate the density of states or perform selected postprocessing, using the current orbitals and one electron energies (IALGO=2) e.g. read from the WAVECAR file.

Mind: except for 'None' and 'Nothing' (which must be spelled out), the first letter determines the applied algorithm. Conjugate, Subrot, Eigenval, None and Nothing are only supported by vasp.5.2.9 and newer versions.

ALGO for response functions and GW calculations and ACFDT/RPA calculations

ALGO=CHI calculates the response functions only.

ALGO=GW0 selects single-shot G₀W₀ calculations or partially selfconsistent GW calculations. The orbitals (wavefunctions) of the previous groundstate calculations are maintained, and G0W0 calculations are performed. If NELM is set, several iterations are performed, and the QP energies are updated in the calculation of G (for details see GW0 calculations).

ALGO=GW selects single-shot G₀W₀ calculations or partially selfconsistent GW calculations. The orbitals of the previous groundstate calculations are maintained, and G0W0 calculations are performed. If NELM is set, several iterations are performed, and the QP energies are updated in the calculation of G AND W (for details see GW calculations).

ALGO=scGW0 selects selfconsistent GW calculations including off-diagonal components of the selfenergy. A full update of the QP energies AND one electron orbitals is performed in the calculation of G only (for details see scGW0 calculations).

ALGO=scGW selects selfconsistent GW calculations including off-diagonal components of the selfenergy. A full update of the QP energies AND one electron orbitals is performed in the calculations of G AND W (for details see scGW calculations).

ALGO=RPA selects RPA total energy calculations see ACFDT/RPA calculations

ALGO=TDHF selects TDHF calculations using the VASP internal Cassida code ACFDT/RPA calculations

ALGO=BSE selects BSE calculations using the VASP internal Cassida code ACFDT/RPA calculations

Examples that use this tag

Contents

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 *{{TAG|ALGO}}=scGW selects selfconsistent ''GW'' calculations including off-diagonal components of the selfenergy. A full update of the QP energies AND one electron orbitals is performed in the calculations of ''G'' AND ''W'' (for details see [[GW recipes#scgw|scGW calculations]]).
-*{{TAG|ALGO}}=RPA selects RPA total energy calculations.
+*{{TAG|ALGO}}=RPA selects RPA total energy calculations see [[ACFDT/RPA calculations]]
+*{{TAG|ALGO}}=TDHF selects TDHF calculations using the VASP internal Cassida code [[ACFDT/RPA calculations]]
+*{{TAG|ALGO}}=BSE selects BSE calculations using the VASP internal Cassida code [[ACFDT/RPA calculations]]
 {{sc|ALGO|Examples|Examples that use this tag}}