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The performance of ten density functional theory (DFT) methods in a prediction of the structure of four clay minerals, in which non-bonding interactions dominate in the layer stacking (dispersive forces in talc and pyrophyllite, and hydrogen bonds in lizardite and kaolinite), is reported. In a set of DFT methods following functionals were included: standard(More)
The adsorption of small alkane molecules in purely siliceous and protonated chabazite has been investigated at different levels of theory: (i) density-functional (DFT) calculations with a gradient-corrected exchange-correlation functional; DFT calculations using the Perdew-Burke-Ernzerhof (PBE) functional with corrections for the missing dispersion forces(More)
An algorithm is proposed for the structural optimization of periodic systems in internal (chemical) coordinates. Internal coordinates may include in addition to the usual bond lengths, bond angles, out-of-plane and dihedral angles, various "lattice internal coordinates" such as cell edge lengths, cell angles, cell volume, etc. The coordinate transformations(More)
The implementation of technique for full structural optimizations of complex periodic systems in the DFT-PAW package VASP, including the volume and shape of the unit cell and the internal coordinates of the atoms, together with a correction that allows an appropriate modeling of London dispersion forces, as given by the DFT-D2 approach of Grimme [Grimme, S.(More)
The energy and gradient expressions for the many-body dispersion scheme (MBD@rsSCS) of Ambrosetti et al (2014 J. Chem. Phys. 140 18A508) needed for an efficient implementation of the method for systems under periodic boundary conditions are reported. The energy is expressed as a sum of contributions from points sampled in the first Brillouin zone, in close(More)
The standard approach to ab initio simulations of activated chemical processes is based on the harmonic-oscillator/rigid-rotor approximation to transition state theory. However, there is increasing evidence that these approximations fail for reactions involving loosely bound reactant and/or transitions states where entropy makes a significant contribution(More)
The dehydrogenation of propane over acidic chabazite has been studied using ab initio density-functional simulations in combination with static transition-state searches and dynamic transition path sampling (TPS) methods at elevated temperatures. The acidic zeolite has been modeled both using a small cluster and a large periodic model consisting of two unit(More)
For organic and hybrid electronic devices, the physicochemical properties of the contained interfaces play a dominant role. To disentangle the various interactions occurring at such heterointerfaces, we here model a complex, yet prototypical, three-component system consisting of a Cu−phthalocyanine (CuPc) film on a(More)
Periodic dispersion corrected DFT calculations have been performed to study the spin-crossover transition of Fe(phen)(2)(NCS)(2) in the molecular and in the crystalline state. We show that London dispersion interactions play a crucial role in the cohesion of the crystals. Based on calculations of vibrational eigenstates of the isolated molecule and of the(More)
The Tkatchenko-Scheffler method for calculating dispersion correction to standard density-functional theory, which uses fixed neutral atoms as a reference to estimate the effective volumes of atoms-in-molecule and to calibrate their polarizabilities and dispersion coefficients, fails to describe the structure and the energetics of ionic solids. Here, we(More)