6533b86efe1ef96bd12cac5d

RESEARCH PRODUCT

A black-box, general purpose quadratic self-consistent field code with and without Cholesky Decomposition of the two-electron integrals

Filippo LippariniJürgen GaussTommaso Nottoli

subject

self-consistent fieldField (physics)Nuclear TheoryBiophysicsHartree–Fock methodsecond-orderFOS: Physical sciencesHartree–FockQuadratic equationBlack boxPhysics - Chemical PhysicsPhysics::Atomic and Molecular ClustersCode (cryptography)Applied mathematicsPhysical and Theoretical ChemistryPhysics::Chemical PhysicsMolecular BiologyMathematicsQuadratic growthCholesky decomposition; Hartree–Fock; Levenberg–Marquardt; second-order; self-consistent fieldChemical Physics (physics.chem-ph)Condensed Matter PhysicsLevenberg–Marquardt algorithmLevenberg–MarquardtCholesky decompositionCholesky decomposition

description

We present the implementation of a quadratically convergent self-consistent field (QCSCF) algorithm based on an adaptive trust-radius optimisation scheme for restricted open-shell Hartree���Fock (ROHF), restricted Hartree���Fock (RHF), and unrestricted Hartree���Fock (UHF) references. The algorithm can exploit Cholesky decomposition (CD) of the two-electron integrals to allow calculations on larger systems. The most important feature of the QCSCF code lies in its black-box nature ��� probably the most important quality desired by a generic user. As shown for pilot applications, it does not require one to tune the self-consistent field (SCF) parameters (damping, Pulay's DIIS, and other similar techniques) in difficult-to-converge molecules. Also, it can be used to obtain a very tight convergence with extended basis sets ��� a situation often needed when computing high-order molecular properties ��� where the standard SCF algorithm starts to oscillate. Nevertheless, trouble may appear even with a QCSCF solver. In this respect, we discuss what can go wrong, focusing on the multiple UHF solutions of ortho-benzyne.

yearjournalcountryeditionlanguage
2021-01-01
https://dx.doi.org/10.48550/arxiv.2106.04836