title: CRYSCOR: a program for the post-Hartree-Fock treatment of periodic systems.
abstract: Cryscor is a periodic post-Hartree-Fock program based on local functions in direct space, i.e., Wannier functions and projected atomic orbitals. It uses atom centered Gaussians as basis functions. The Hartree-Fock reference, as well as symmetry information, is provided by the Crystal program. Cryscor presently features an efficient and parallel implementation of periodic local second order Møller-Plesset perturbation theory (MP2), which allows us to study 1D-, 2D- and 3D-periodic systems beyond 1000 basis functions per unit cell. Apart from the correlation energy also the MP2 density matrix, and from that the Compton profile, are available. Very recently, a new module for calculating excitonic band gaps at the uncorrelated Configuration-Interaction-Singles (CIS) level has been added. Other advancements include new extrapolation techniques for calculating surface adsorption on semi-infinite solids. In this paper the diverse features and recent advances of the present Cryscor version are illustrated by exemplary applications to various systems: the adsorption of an argon monolayer on the MgO (100) surface, the rolling energy of a boron nitride nanoscroll, the relative stability of different aluminosilicates, the inclusion energy of methane in methane-ice-clathrates, and the effect of electron correlation on charge and momentum density of α-quartz. Furthermore, we present some first tentative CIS results for excitonic band gaps of simple 3D-crystals, and their dependence on the diffuseness of the basis set.
authors.affiliation: Dipartimento di Chimica IFM, and Centre of Excellence NIS (Nanostructured Interfaces and Surfaces), Università di Torino, via Giuria 5, I-10125 Torino, Italy.
authors.forename: Cesare
authors.initials: C
authors.lastname: Pisani
authors.forename: Martin
authors.initials: M
authors.lastname: Schütz
authors.forename: Silvia
authors.initials: S
authors.lastname: Casassa
authors.forename: Denis
authors.initials: D
authors.lastname: Usvyat
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Maschio
authors.forename: Marco
authors.initials: M
authors.lastname: Lorenz
authors.forename: Alessandro
authors.initials: A
authors.lastname: Erba