Discrete variational Xa method

The first international workshop on the Discrete Variational Xa method was held on September 2 and 3,1996 with great success in Debrecen, Himgary, which was well organized by active members of ATOMKI in Himgarian Academy of Science, especially by L. Kover. The memorial year of 1996 for our DV-Xa society coincided fortimately also with 1100 years of the Hungarian independence. This seems to celebrate the independence or distinguishability of the DV-Xa method from the other numerous molecular orbital calculation methods. 

Cls photoemission shakeup satellites for the CO molecule were calculated with the spin-polarized discrete variational Xa method. The transition state method was applied to the estimation of multiplet peak positions for the shakeup transitions and the results are in reasonable agreement with the experimental values. 

Auger Spectrum. The Auger spectrum of NH4 was calculated using a scattered-wave (discrete-variational Xa) method. In the low-energy region it was found to be similar to an experimental N KVV Auger spectrum of NH4CI [42, 43]. 

In the present calculation, we used two ab initio methods to investigate structural stability and the potential for carrier generation of X B6 and X Bi2 clusters in c-Si. Here X is from H to Br in the periodic table. The following two methodsused were (i) plane wave ultrasoft pseudopotential method for the optimization of atomic structures and (ii) discrete variational-Xa (DV-Xa) molecular orbital method for the analysis of the fine electronic structures and activation energies of the clusters. 

The electronic structures of a series of models were calculated using the first-principles discrete variational-Xa (DV-Xa) molecular orbital (MO) method with a... 

This volume is a collection of the papers presented at the 4th International Conference on DV-Xa Method (DV-Xa 2006). This conference was organized by the Society for Discrete Variational Xa (Japan) and Sunchon National University (Korea). A subtitle set to the conference was the Industrial-Academic Cooperation Symposium and the 19th DV-Xot Annual Meeting. The primary objective of the conference was the promotion and development of science and technology on the basis of the DV-Xx molecular orbital method. 

Cluster type molecular orbital calculations have proven to be powerful tools for understanding the electronic structure of molecules, clusters and solids. The Discrete Variational Xa (DV-Xa) is one of the most versatile amongst these methods in interpreting spectroscopic results and for predicting properties of polyatomic systems of great practical importance. 

This volume includes the papers of Keynote Lectures and Invited Contributions presented at the First International Workshop on DV-Xa Method (DV-Xa 96, with Special Emphasis on Inner-Shell Physics and Chemistry). The Workshop was organized by the Society for Discrete Variational Xa (Japan), the Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), and the Department of Theoretical Physics of the L. Kossuth University of Debrecen, following numerous annual meetings on this topic in Japan. 

In order to comprehensively show the chemical dissociation process of CO on metal surfaces, electronic structure calculations have been performed for simple models. We have chosen two methods for the present analyses. The first method is the Discrete Variational Xa (DV-Xa) method, which is the first-principles molecular orbital calculation using Slater s Xa fimctional for the electron many body term [21]. This method is applied for the electronic structural analyses of CO adsorption on metal surfaces. The second method is the Full-Potential Linear Muffin-Tin Orbital (FP-LMTO) method, which is the first-principles band structure calculation method [22]. The FP-LMTO implementation code of LmtART [23, 24] is used for the calculations of the density of states (DOS) of non-magnetic fee iron phase. We discuss the electronic structure of transition metal alloys from the rigid band analyses using this DOS. The local density approximation (LDA) parameterized by Vosko et al. [25] is used for the present FP-LMTO calculations. The tetrahedron... 

It is of interest that atomic hydrogen centres, which are unstable even at 4 K in quartz, were observed in both coesite and stishovite at 77K.66 The electron centre associated with Ti impurity was observed in stishovite, but not clearly in coesite. Electronic structures of these paramagnetic centres were calculated with the discrete variational (DV)-Xa method to establish a model for centres having substitutional impurities of Al, Ge and Ti.67... 

Other Related Methods.—Baerends and Ros have developed a method suitable for large molecules in which the LCAO form of the wavefunction is combined with the use of the Xa approximation for the exchange potential. The method makes use of the discrete variational method originally proposed by Ellis and Painter.138 The one-electron orbitals are expanded in the usual LCAO form and the mean error function is minimized. 

The present author found a non-empirical method to describe the antiferromagnetic state of transition metal oxides and hydrogen clusters with a relatively long H-H distance [1-3]. The study used the discrete variational (DV)-Xa molecular orbital theory, which has been successfully applied to analyze properties of... 

Abstract The discrete variational (DV)-Xa method was used to analyze the high-resolution soft X-ray absorption spectra (XAS) in the C /Cregion of sputtered amorphous carbon films and carbon black to elucidate their local structures. The measured XAS of amorphous carbon and carbon black were compared with those of reference compounds, and the fine structure in the XAS can be assigned by the calculated density of states of the reference compounds. Such a comparative analysis in the measured XAS and the calculated density of states of these carbon materials with reference compounds, which have been known their local or molecular structures, is a valid approach for elucidating the complex local structures of carbon materials. 

IR, Raman, NMR, ESR, UPS, XPS, AES, EELS, SIMS) [1]. However, some industrial carbon materials such as amorphous carbon films and carbon black cannot be easily characterized from the local-structure point of view by these methods, because these materials usually take amorphous and complex structures. Recently, soft X-ray emission and absorption spectroscopy using highly brilliant synchrotron radiation [2] has been utilized to characterize various carbon materials, because information on both the occupied and unoccupied orbitals, which directly reflect the local structure and chemical states, can be provided from the high-resolution soft X-ray measurements. We have applied the soft X-ray spectroscopy to elucidate the local structure and chemical states of various carbon materials [3]. Additionally, we have successfully used the discrete variational (DV)-Xa method [4] for the soft X-ray spectroscopic analysis of the carbon materials, because the DV-Xa method can easily treat complex carbon cluster models, which should be considered for the structural analysis of amorphous carbon materials. 

The situation with II-VI semiconductors such as ZnO is similar to the situation with the elemental and the III-V semiconductors in respect of the location of the impurity atoms and their influences on the electric property. It is reported in ZnO that P, As, or S atom replaces either Zn or O site, and a part of them are also located at an interstitial site, as well as at a substitutional site [2,5-7], The effect of a few kind of impurities such as group-IIIA and -VA elements on the electric property of ZnO was extensively studied, especially when the impurity atoms were located at a substitutional site. The effects of the greater part of elements in the periodic table on the electric property of ZnO are, however, not well understood yet. The purpose of the present study is to calculate energy levels of the impurity atoms from Li to Bi in the periodic table, to clarify the effect of impurity atoms on the electric property of ZnO. In the present paper, we consider double possible configuration of the impurity atoms in ZnO an atom substitutes the cation lattice site, while another atom also substitutes the anion sublattice site. The calculations of the electronic structure are performed by the discrete-variational (DV)-Xa method using the program code SCAT [8,9],... 

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