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 semiinfinite 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 a-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.

Silica Surface Features and Their Role in the Adsorption of Biomolecules: Computational Modeling and Experiments

“…Local correlation methods, [375][376][377][378][379][380][381][382][383] allow exploiting the fundamental local character of dynamical electron correlation, leading to methods that may scale linearly with the size of the system and thus largely reducing the computational costs of post-Hartree-Fock methods. As already anticipated in section 4.1, it is worth mentioning that local-MP2 has been implemented for extended systems by exploiting the translational and point symmetry poperties of crystalline structures 384 with the periodic boundary conditions as implemented in the CRYSCOR program, 328 and in the VASP program 330 through the random phase approximation associated to exact exchange. 329 These methods are, in general, very expensive when applied to extended systems but the development of codes apt to exploit the power of the high performance computing architectures 332 will soon make this kind of calculations available to the scientific community.…”

“…The disadvantage is that the maximum level of theoretical method applicable to periodic systems is limited to the DFT approach due to the difficulty of extending the higher correlated methods based on the wave function expansion to solid state treatment. Recent progress has, however, been done both in the direction of the periodic implementation of the MP2 method in its localized definition 327 in the CRYSCOR program 328 and methods based on the random phase approximation associated to exact exchange 329 coded in the VASP program. 330 In general these approaches are rather expensive and the geometries cannot be coherently optimized as the analytical energy gradient…”

Response Properties of Periodic Materials Subjected to External Electric and Magnetic Fields

“…Another longer-term perspective is the development of optical properties calculations for solids at the post-Hartree-Fock level. This could be done in connection with the local-correlation CRYSCOR code, [47,48,49] which presently features a very efficient implementation of the local MP2 approach for periodic systems. This implementation makes use of advanced techniques such as density fitting [38] and orbital-specific virtuals [62], as well as efficient parallel implementation.…”

Approaching an exact treatment of electronic correlations at solid surfaces: The binding energy of the lowest bound state of helium adsorbed on MgO(100)

“…Such a situation calls for an ab initio treatment in which the exact answer can be approached systematically. It is only very recently that such a treatment became applicable to periodic systems [20,21].For the He-MgO(100) system there are several experimental studies in the literature reporting the energy of the ground state of adsorbed He [4,18,22,23]. In adsorption isotherm measurements of MgO smoke [23], a value of −4.8 meV for the adsorption energy was obtained.…”

“…The periodic LMP2 potential-energy surface (PES) was calculated as the interaction energy per helium atom between a (100) MgO three-layer slab (with an experimental lattice parameter of 4.211Å) and a square monolayer of helium matching the surface lattice of MgO. The three-layer slab was extrapolated to the bulk limit by employing the slab replication technique [20]. Further technical details of the calculations are given in Appendix A.…”