VESTA is a three-dimensional visualization system for crystallographic studies and electronic state calculations. It has been upgraded to the latest version, VESTA 3, implementing new features including drawing the external mor­phology of crystals; superimposing multiple structural models, volumetric data and crystal faces; calculation of electron and nuclear densities from structure parameters; calculation of Patterson functions from structure parameters or volumetric data; integration of electron and nuclear densities by Voronoi tessellation; visualization of isosurfaces with multiple levels; determination of the best plane for selected atoms; an extended bond-search algorithm to enable more sophisticated searches in complex molecules and cage-like structures; undo and redo in graphical user interface operations; and significant performance improvements in rendering isosurfaces and calculating slices.

VESTA 3 for three-dimensional visualization of crystal, volumetric and morphology data

CASTEP Computer program / Density functional theory / Pseudopotentials / ab initio study / Plane-wave method / Computational crystallography Abstract. The CASTEP code for first principles electro- nic structure calculations will be described. A brief, non- technical overview will be given and some of the features and capabilities highlighted. Some features which are un- ique to CASTEP will be described and near-future devel- opment plans outlined.

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First principles methods using CASTEP

First-principles simulation, meaning density-functional theory calculations with plane waves and pseudopotentials, has become a prized technique in condensed-matter theory. Here I look at the basics of the suject, give a brief review of the theory, examining the strengths and weaknesses of its implementation, and illustrating some of the ways simulators approach problems through a small case study. I also discuss why and how modern software design methods have been used in writing a completely new modular version of the CASTEP code.

https://iopscience.iop.org/article/10.1088/0953-8984/14/11/301/pdf

First-principles simulation: ideas, illustrations and the CASTEP code

The surface science of titanium dioxide

TiO2 photocatalysis and related surface phenomena

Using first-principles calculations we show that the adsorption of atomic hydrogen on graphene opens a substantial gap in the electronic density of states in which lies a spin-polarized gap state. This spin is quenched by the presence of a rotated C-C bond (a Stone-Wales defect) adjacent to or distant from the H atom. We explain these findings and discuss the implications for nanotubes and magnetic nanographene. Furthermore, we demonstrate that the combined effect of high curvature and a Stone-Wales defect makes H2 chemisorption close to being thermodynamically favorable.

/pdf/hallmark-of-perfect-graphene-42ow109w9g.pdf

Hallmark of Perfect Graphene

Using first-principles density-functional methods we show that a monolayer of water on the rutile (110) surface contains H2O in both molecular and dissociated forms. Intermolecular hydrogen bonding stabilizes this configuration with respect to the complete dissociative adsorption which would be predicted from studies at lower coverage. The proposed mixed adsorption mode is fully consistent with experimental data, reconciles apparent conflicts within these data, and explains discrepancies between experiment and previous calculations.

/pdf/mixed-dissociative-and-molecular-adsorption-of-water-on-the-5a2qbeajh4.pdf

Mixed dissociative and molecular adsorption of water on the rutile (110) surface

We have performed plane-wave pseudopotential density-functional theory calculations on the stoichiometric and reduced TiO2 ~110! surface, the 231 and 132 reconstructions of the surface formed by the removal of bridging-oxygen atoms, and on the oxygen vacancy in the bulk. The effect of including spin polarization is investigated, and it is found to give a qualitatively different electronic structure compared with a spin-paired description. In the spin-polarized solutions, the excess electrons generated by oxygen reduction occupy localized band-gap states formed from Ti (3d) orbitals, in agreement with experimental findings. In addition, the inclusion of spin polarization substantially lowers the energy of all the systems studied, when compared with spin-paired solutions. However, spin-polarization does not change the relative stability of the two reconstructions, which remain energetically equivalent. @S0163-1829~97!02724-0#

Philip J. D. Lindan

Papers

First-principles simulation: ideas, illustrations and the CASTEP code

Hallmark of Perfect Graphene

Mixed dissociative and molecular adsorption of water on the rutile (110) surface

First-principles spin-polarized calculations on the reduced and reconstructed tio2 (110) surface

First-principles molecular dynamics simulation of water dissociation on TiO2 (110)