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Title: Analytical gradients of the state-average complete active space self-consistent field method with density fitting

An efficient implementation of the state-averaged complete active space self-consistent field (SA-CASSCF) gradients employing density fitting (DF) is presented. The DF allows a reduction both in scaling and prefactors of the different steps involved. The performance of the algorithm is demonstrated on a set of molecules ranging up to an iron-Heme b complex which with its 79 atoms and 811 basis functions is to our knowledge the largest SA-CASSCF gradient computed. For smaller systems where the conventional code could still be used as a reference, both the linear response calculation and the gradient formation showed a clear timing reduction and the overall cost of a geometry optimization is typically reduced by more than one order of magnitude while the accuracy loss is negligible.
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [1] ;  [4]
  1. Department of Chemistry – Ångström, The Theoretical Chemistry Programme, Uppsala University, P.O. Box 518, 751 20 Uppsala (Sweden)
  2. Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, 0315 Oslo (Norway)
  3. (Italy)
  4. (Sweden)
Publication Date:
OSTI Identifier:
22493444
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 4; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ALGORITHMS; ATOMS; DENSITY; HEME; IMPLEMENTATION; IRON; LOSSES; MOLECULES; OPTIMIZATION; PERFORMANCE; REDUCTION; SELF-CONSISTENT FIELD; SPACE