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A slab approach in the framework of ab initio calculations was applied to study surface electronic states in In2O3 crystal. Density functional theory (DFT) calculations were carried out employing the WIEN 2k code and using the full potential method with Augmented Plane Waves + local orbitals (APW+lo) formalism. Total and partial DOS (Density of States) were calculated for In and O atoms in two upper (110) surface layers. Comparison of total and partial DOS allowed determining a contribution of electronic states of different In and O surface atoms into formation of surface electronic spectra and corresponding chemical bonds. A dominant ionic character of chemical bonds in In2O3 is found. Calculations were performed for three slab models with different geometry parameters. It was shown that an optimal ratio between the whole vertical size of a supercell and the vertical size of atomic cluster has to be chosen. The size of vacuum region in the slab model influences significantly on the reliability of calculated characteristics of the surface electronic structure. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

Ab initio calculations of the properties of the FeAl B2 phase alloyed by Cr or V are performed on the basis of the full potential augmented plane-wave (APW) + local orbitals (lo) method. The site preference occupation for Cr and V atoms in this compound is investigated. We studied the changes in the site preference for Cr and V substituting for Fe or Al when the vacancy on the Fe site is formed. Existence of the vacancy significantly changes the site occupation preference for Cr that transits from the Al site to the Fe site. The site occupation preference for these alloying elements in the compound is explained in terms of the electronegativity of surrounding atoms and the effective charges of transition metals. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005

We performed nonempirical simulations of the properties of the tungsten Σ3(111) grain boundary (GB) with a boron atom and demonstrate the influence of many-body interactions on the resistance of the GB with respect to sliding. We also studied the propagation of relaxations in the vicinity of the GB. The many-body interatomic potentials (IP) used in these simulations were obtained with the recursion procedure from ab initio total energy calculations. At each step of the slip process, the equilibrium positions of the atoms near GB were calculated with the generalized simulated annealing technique. It was demonstrated how the sliding shift influences the penetration of the elastic field inside the grain. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002

Nonempirical study of the site preference occupation for Ni, Ti, and Cr substituting for Fe in Fe 0 . 7 5 - x Me x Al 0 . 2 5 has been carried out for a number of Me dopant concentrations in the framework of the coherent potential approximation. Obtained values of total energies confirmed experimental observations that Ni atoms occupy the sublattice Fe(1) (see Fig. 1), Ti atoms occupy the sublattice Fe(2), and Cr atoms do not show any preference in substitution of Fe in Fe 0 . 7 5 - x Me x Al 0 . 2 5 . We demonstrated also that Ni addition to Fe 0 . 7 5 - x Me x Al 0 . 2 5 does not change the type of bonding in Fe 0 . 7 5 - x Ni x Al 0 . 2 5 , while Cr and Ti additions lead to sufficient hybridization of d-electrons.

A hybrid approach is described, which combines stochastic classical molecular dynamics and first-principles density functional theory to model the atomic structure and properties of large solid-state systems. The stochastic molecular dynamics using generalized simulated annealing (GSA) is based on nonextensive statistical mechanics and thermodynamics. Examples of applications are given on metalloid impurities in metals. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001

Vacancies in metal are studied in the model of the atom-vacancy solid solution. Vacancy formation energy is discussed in terms of cluster expansion formalism. It is shown that effective interaction of vacancies is formally included in the energy of vacancy formation. The cluster expansion method illustrates that pairwise and nonpairwise interactions between atoms and vacancies are responsible for the interaction of vacancies in the atom-vacancy solid solution. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001

A scheme to produce density-of-states-(DOS)-dependent potentials for d-metals on the basis of the local density approximation calculations is suggested. As an example this scheme is applied to construct a DOS-dependent potential for tungsten. The second moment of the tungsten DOS is calculated. The authors show that the obtained potentials give a good agreement of cohesive properties with the experimental data.

In the nonempirical approach based on the coherent potential approximation (CPA), we investigate the concentration dependence of the energy parameters which describe the stability of the disordered Fe–Al alloy and the phase transformation in B2 and DO3 phases. We based our calculations on the most attractive feature of CPA to be applicable to the direct calculations of the electronic structure of random or partially ordered alloys. The procedure described in our study [D. Fuks and S. Dorfman, Solid State Commun. 90, 773 (1994)] for the estimation of the parameters of the effective mixing potential is realized for different phases in the stoichiometric composition. Calculation data for different concentrations of Fe–Al alloy are used to extract the interaction parameters V(0), V(k1), and V(k2). These energy parameters are compared with the parameters treated from the diffuse X-ray scattering data. We show that the interaction parameters for Fe–Al alloys strongly depend on the concentration. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 75: 927–941, 1999

In the framework of the coherent potential approximation the authors show that the interaction parameter for disordered Fe-Al alloy strongly depends on the concentration. The calculations were provided within linear muffin-tin orbital formalism in the atomic sphere approximation. Calculation data for B2 phase for different concentrations were used to extract the interaction parameter, V(0), for disordered solid solutions and were compared with the parameter treated from the X-ray scattering data. The concentration dependence of V(0) leads to the failure of the application of the regular solid solution model to the study of the phase relations in the Fe-Al system. Parameter V(k{sub s}), which is responsible for ordering tendency, also depends on concentration, and it is in accordance with the experimental data.

The preferable carbon occupation in copper-based solid solutions is modeled in different CuC lattice cells and clusters. A study is based on the comparative analysis of electronic density distributions for different interatomic distances, supercell configurations, and compositions of carbon. For these solid solutions we use the linear muffin-tin orbitals (LMTO) and discrete variation method (DVM) computer codes which allow us to calculate equilibrium positions of carbon atoms. We study the concentration dependence of the lattice parameter in CuC solid solution and discuss the charge transfer in this system. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 1085–1092, 1998

On the basis of a nonempirical pair potential, the temperature dependencies of the long-range-order parameter of NiTi and AuPd are calculated. The suggested effective potential approach allows one to describe the changes in phase relations. The evaluation of the internal mixing energy of alloys is carried out in the framework of the static concentration waves theory of Khachaturyan. The model outlines the technique to calculate the values of the energy parameters of the ordering process from first principles. © 1996 John Wiley & Sons, Inc.

The assumption of the concentration dependence of the energy of formation of vacancy-type defects (VTD) in solids is applied to the procedure of the estimation of the defect interaction parameters. The VTD effective interaction is described by the mixing potential. The sign of this potential characterizes the stability of the VTD-atom “alloy.” Employing the example of Nb, we illustrate the ability of the suggested approach to describe the stability of the VTD-atom “alloy.” © 1996 John Wiley & Sons, Inc.

The effective interaction potential for tungsten is used to calculate the second moment of phonon spectrum, , Debye temperature, and cohesive properties. It is shown that the potentials obtained give good agreement of cohesive properties with the data calculated from the universal function of Rose et al. The applicability of the atomic sphere approximation to the calculation of the integral thermodynamic properties of tungsten is discussed. The convergence of in real space is studied; we find that the main contribution to is given by the first coordination shell. The Gibbs–Bogoliubov inequality and the variational procedure of Ross are used to calculate the temperature dependence of free energy in liquid tungsten. The thermodynamic functions obtained for solid and liquid phases are employed in determination of the melting temperature. © 1995 John Wiley & Sons, Inc.