title: Full Parallel Implementation of an All-Electron Four-Component Dirac-Kohn-Sham Program.
abstract: A full distributed-memory implementation of the Dirac-Kohn-Sham (DKS) module of the program BERTHA (Belpassi et al., Phys. Chem. Chem. Phys. 2011, 13, 12368-12394) is presented, where the self-consistent field (SCF) procedure is replicated on all the parallel processes, each process working on subsets of the global matrices. The key feature of the implementation is an efficient procedure for switching between two matrix distribution schemes, one (integral-driven) optimal for the parallel computation of the matrix elements and another (block-cyclic) optimal for the parallel linear algebra operations. This approach, making both CPU-time and memory scalable with the number of processors used, virtually overcomes at once both time and memory barriers associated with DKS calculations. Performance, portability, and numerical stability of the code are illustrated on the basis of test calculations on three gold clusters of increasing size, an organometallic compound, and a perovskite model. The calculations are performed on a Beowulf and a BlueGene/Q system.
authors.affiliation: Istituto di Scienze e Tecnologie Molecolari, Consiglio Nazionale delle Ricerche c/o Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia , Via Elce di Sotto 8, 06123 Perugia, Italia.
authors.forename: Sergio
authors.initials: S
authors.lastname: Rampino
authors.affiliation: Istituto di Scienze e Tecnologie Molecolari, Consiglio Nazionale delle Ricerche c/o Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia , Via Elce di Sotto 8, 06123 Perugia, Italia.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Belpassi
authors.affiliation: Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia , Via Elce di Sotto 8, 06123 Perugia, Italia.
authors.forename: Francesco
authors.initials: F
authors.lastname: Tarantelli
authors.affiliation: Dipartimento di Farmacia, Università degli Studi 'G. D'Annunzio' , Via dei Vestini 31, 66100 Chieti, Italia.
authors.forename: Loriano
authors.initials: L
authors.lastname: Storchi