Open AccessSecond-Order CASSCF Algorithm with the Cholesky Decomposition of the Two-Electron Integrals
Author(s) -
Tommaso Nottoli,
Jürgen Gauß,
Filippo Lipparini
Publication year - 2021
Publication title -
journal of chemical theory and computation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.001
H-Index - 185
eISSN - 1549-9626
pISSN - 1549-9618
DOI - 10.1021/acs.jctc.1c00327
Subject(s) - cholesky decomposition , hessian matrix , complete active space , computer science , benchmark (surveying) , basis (linear algebra) , algorithm , decomposition , basis function , minimum degree algorithm , computational chemistry , chemistry , mathematics , incomplete cholesky factorization , basis set , physics , density functional theory , quantum mechanics , eigenvalues and eigenvectors , geodesy , geometry , organic chemistry , geography
In this contribution, we present the implementation of a second-order complete active space-self-consistent field (CASSCF) algorithm in conjunction with the Cholesky decomposition of the two-electron repulsion integrals. The algorithm, called norm-extended optimization, guarantees convergence of the optimization, but it involves the full Hessian and is therefore computationally expensive. Coupling the second-order procedure with the Cholesky decomposition leads to a significant reduction in the computational cost, reduced memory requirements, and an improved parallel performance. As a result, CASSCF calculations of larger molecular systems become possible as a routine task. The performance of the new implementation is illustrated by means of benchmark calculations on molecules of increasing size, with up to about 3000 basis functions and 14 active orbitals.