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density_fitting [2020/06/11 18:17]
127.0.0.1 external edit
density_fitting [2020/09/28 16:58]
werner
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 ====== Density fitting ====== ====== Density fitting ======
  
-Density fitting can be used to approximate the integrals in spin restricted Hartree-Fock (''HF''), density functional theory (''KS''), second-order Møller-Plesset perturbation theory (''MP2'' and ''RMP2''), explicitly correlated MP2 (MP2-F12), all levels of closed-shell local correlation methods (''LCC2'', ''LMP2''-''LMP4'', ''%%LQCISD(T)%%'', ''%%LCCSD(T)%%''), as well as for ''CASSCF'' and ''CASPT2'' methods. Density fitting is invoked by adding the prefix ''DF-'' to the command name, e.g. ''DF-HF'', ''DF-KS'', ''DF-MP2'' and so on. Gradients are available for ''DF-HF'', ''DF-KS'', ''DF-MP2'', ''DF-LMP2'', ''DF-CASSCF'', and ''DF-CASPT2''. Symmetry is not implemented for density fitting programs. Therefore, symmetry is turned off automatically if DF- is found in the input.+Density fitting can be used to approximate the integrals in spin restricted Hartree-Fock (''HF''), density functional theory (''KS''), second-order Møller-Plesset perturbation theory (''MP2'' and ''RMP2''), explicitly correlated MP2 (MP2-F12), all levels of closed-shell local correlation methods (''LCC2'', ''LMP2''-''LMP4'', ''%%LQCISD(T)%%'', ''%%LCCSD(T)%%''), as well as for ''CASSCF'' and ''CASPT2'' methods. Density fitting is invoked by adding the prefix ''DF-'' to the command name, e.g. ''DF-HF'', ''DF-KS'', ''DF-MP2'' and so on. Gradients are available for ''DF-HF'', ''DF-KS'', ''DF-MP2'', ''DF-LMP2'', ''DF-CASSCF'', and ''DF-CASPT2''. Symmetry is implemented for energy calculations (without gradients) for ''DF-RHF''''DF-RKS'',''DF-UHF'', ''DF-UKS'' ''DF-RMP2'',''DF-RMP2-F12'', ''DF-CASSCF|DF-MULTI'', ''DF-CASPT2|DF-RS2'', and ''DF-RS2C'', 
 +but for ''DF-MP2'', ''DF-CCSD'' (and variants) as well as for local methods symmetry is not implemented and automatically turned off.
  
 By default, a fitting basis set will be chosen automatically that corresponds to the current orbital basis set and is appropriate for the method. For instance, if the orbital basis set is ''VTZ'', the default fitting basis is ''%%VTZ/JKFIT%%'' for ''DF-HF'' or ''DF-KS'', and ''%%VTZ/MP2FIT%%'' for ''DF-MP2''. Other fitting basis sets from the library can be chosen using the ''DF_BASIS'' option, e.g. By default, a fitting basis set will be chosen automatically that corresponds to the current orbital basis set and is appropriate for the method. For instance, if the orbital basis set is ''VTZ'', the default fitting basis is ''%%VTZ/JKFIT%%'' for ''DF-HF'' or ''DF-KS'', and ''%%VTZ/MP2FIT%%'' for ''DF-MP2''. Other fitting basis sets from the library can be chosen using the ''DF_BASIS'' option, e.g.