Two-component relativistic density functional theory combined with high-level ab initio correlation techniques was applied to the study of the electronic structure and isomerism of Au(3). All calculations were performed with accurate small-core shape-consistent relativistic pseudopotentials. Density functional theory was used to determine the equilibrium structures of the Au(3) isomers and isomerization path and to estimate the contributions of spin-orbit effects to the ground state electronic energy along the path. The reliability of these estimates was verified through independent many-body multipartitioning perturbation theory calculations. Spin-orbit corrections were used to refine the isomerization energy profile computed by spin-orbit-free coupled cluster methods.
A cluster modeling of the interaction of an eka-Pb atom with the stable Au(111) surface using accurate small-core relativistic pseudopotentials and two-component non-collinear DFT is reported. The results obtained with two different types of exchange-correlation functionals (generalized-gradient and hybrid) are generally consistent and give rise to E114/Au(111) adsorption energy estimates within the range 0.4-0.5 eV. Substantial differences between the E114-Au and Pb-Au interactions are further corroborated.
Present-day computational techniques provide a possibility of evaluating properties of macrosystems using ab initio quantum chemistry and theories of elementary processes. Physical and chemical phenomena on very different timescales have to be taken into account (excitation, emission, chemical reactions, diffusion) at different levels of refining. This refining covers a very wide region of parameters starting from the structure of species up to the macro chemical mechanism of their conversion. This multilevel approach is described in detail in the paper and includes interaction and data transfer between different levels of phenomena description. In the framework of the approach, unknown properties of molecules, ions and atoms (structure, potential energy curves, transition dipole moments) are calculated based on quantum-chemical methods. The calculation results are used to evaluate rate characteristics of physical and chemical processes. The developed kinetic state-to-state scheme is then used to calculate the macro properties of the system under investigation. As an example of the multilevel approach, the emission properties of the Ar–GaI3 positive column discharge plasma were calculated using the Chemical Work Bench computational environment. The calculations yield the electron energy balance and emission efficiency as functions of plasma parameters.
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