MolSOC: A spin–orbit coupling code

Abstract

A description of the theoretical background, the numerical algorithm and the input/output files structures of the computer program MolSOC is presented. This code provides an efficient tool for the spin–orbit (SO) coupling treatment in many-electron systems by a non-iterative method implementation. Preliminary versions of the MolSOC program have been already tested and successfully applied in the framework of density functional theory (DFT). SO calculations can be performed either employing a full SO operator or a reduced screened nuclear-charge operator. With the second option, the required computational time can be significantly reduced. However, it has been previously demonstrated that the full SO operator can be successfully applied to extended molecular systems. Finally, practical instructions for the program use are also included. Program summaryProgram title: MolSOC v0.1Catalogue identifier: AERK_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AERK_v1_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.: 13333No. of bytes in distributed program, including test data, etc.: 2301930Distribution format: tar.gzProgramming language: Fortran 90.Computer: All Linux based workstations.Operating system: Linux.Classification: 16.1.External routines: Subset of BLAS and LAPACK routines (included in the distribution file).Nature of problem:An accurate description of the electronic structure of heavy many electron systems requires, very often, the inclusion of the spin–orbit coupling contributions.Solution method:Spin–Orbit matrix elements can be computed between optimized states at the density functional theory level using the full Breit–Pauli operator or a reduced screened nuclear-charge operator.Running time:It depends on the size of the chemical system, on the basis set used and on the computational method used. The tests included only take seconds or a few minutes to run.