A major reason for the departure of core level X-ray photoelectron spectra ~XPS! of transition metal cations in oxides from the predictions of atomic models is shown to arise from ligand field splittings in the initial state of photoemission. This splitting often leads to a change in the spatial degeneracy of the initial state but the consequences of this for XPS have not been explicitly identi...

In this study, we use first principles multiple scattering calculations on atomic clusters to show how the carbon and nitrogen K-edge fine structures are modified in the vicinity of structural defects in TiN and TiC. Changes in the electron energy loss spectra are due to changes in the atomic structure of the first atomic shells around the absorbing atom. Two different kinds of defects, which b...

We propose a novel unsupervised learning framework to model activities and interactions in crowded and complicated scenes. Under our framework, hierarchical Bayesian models are used to connect three elements in visual surveillance: low-level visual features, simple “atomic” activities, and interactions. Atomic activities are modeled as distributions over low-level visual features, and multiagen...

Graphene and its analogues offer a broad range of application opportunities for (opto)-electronics, sensing, catalysis, phase separation, energy conversion storage, etc. Engineering graphene properties often relies on controllable functionalization, defect formation patterning, reactive gas etching. In this chapter, we survey the dynamics using classical quantum-classical methods. We discuss re...

The cluster representation matrices have already been successfully used to enumerate close-packed vacancy clusters in all single-lattice crystals [I, 2]. Point defect clusters in double-lattice crystals may have identical geometry but are distinct due to unique atomic postions enclosing them. The method of representation matrices is extended to make it applicable to represent and enumerate ...

Abstract The atomic cluster expansion is a general polynomial of the energy in multi-atom basis functions. Here we implement performant C++ code that suitable for use large-scale atomistic simulations. We briefly review and give detailed expressions energies forces as well efficient algorithms their evaluation. demonstrate implemented shifts previously established Pareto front machine learning ...