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Next: 17.3 Orbital localization Up: 17 Local correlation treatments Previous: 17.1 Introduction   Contents   PDF

17.2 Invoking local correlation methods

The local correlation treatment is switched on by preceding the command name by an L, i.e., by using the LMP2, LMP3, LMP4, LQCISD, LCCSD, or LCISD commands.

The LQCISD and LCCSD commands can be appended by a specification for the perturbative treatment of triple excitations, e.g. LCCSD(T). Density fitting can be invoked by prepending the command name by DF-, e.g. DF-LMP2, DF-LCCSD(T), DF-LCCSD(T)-F12 etc. In density fitting calculations an additional auxiliary basis set is needed. Details about choosing such basis sets and other options for density fitting are described in sections 16.

The general input for local coupled LMP2 or coupled cluster calculations with density fitting (recommended) is:

DF-LMP2,options
Local MP2 calculation
DF-LCCSD,options
Local CCSD calculation (includes DF-LMP2)
DF-LCCSD(T),options
Local density fitted CCSD(T) calculation (include DF-LMP2 and DF-LCCSD)

The explicitly correlated counterparts are

DF-LMP2-F12,options
DF-LCCSD-F12,options
DF-LCCSD(T)-F12,options

There are many options and directives to control the local approximations (e.g., domains and pair classes). Here we only described the most important ones. For a full description please read the MOLPRO users manual.



Next: 17.3 Orbital localization Up: 17 Local correlation treatments Previous: 17.1 Introduction   Contents   PDF

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molpro@molpro.net 2017-12-10