DV Xa method

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... 

Imoto has reported calculations of the electronic structures of the model compounds [Mo6E8(PH3)6] (E = S, Se) by the DV Xa method (53-55, 66). Oh symmetry is assumed for the Mo6 cluster. Stepwise calculations beginning from the Mo6 cluster, followed by the inclusion... 

The electronic levels of a model compound [Mo4S6Cl2(PH3)6] have been calculated by the DV-Xa method (100). In a cluster of C2A symmetry, five metal—metal bonding orbitals (two ag, one au, one bg, and one bu) are expected. These orbitals are strongly mixed with the ligand orbitals and show large HOMO-LUMO gaps (Fig. 24), which may be the characteristics of the electron-precise clusters with 10 electrons. 

The next step to reach to our aims is to determine the localized molecular orbitals of the anionic group. Of course, there are many methods available for the calculations of molecular orbitals in our theory, such as the various approximation methods and even the recently developed Dv-Xa method discussed in quantum chemistry. But, in view of the nature of the basic assumptions in our theory, the CNDO approximation seems to be suitable for calculations of SHG coefficients when the anionic groups consist of elements from the first, second and third families in the periodic table. EHMO type approximations are suitable for other elements, particularly if transition metal elements take part in the ionic groups or molecules. It is not necessary to use higher approximations. 

In the present work we first perform molecular orbital (MO) calculations using the relativistic DV-Xa method. Then we perform Cl calculations using the DVME method to obtain the energy levels and wave functions of a many-electron system, which will be used for calculations and analysis of the optical spectra of RE ions in crystals. 

Invited 17. Hisashi Yoshida and Kazuyoshi Ogasawara (NEC Lighting, Ltd., Kwansei Gakuin University) A Novel Study of Phosphors using Relativistic DV-Xa Method... 

As a solution to this problem we have tried the application of Madelung potential [2] to the semiconductor crystals. Till now, the trial has not been carried out in the semiconductor crystals to our knowledge except our presentation at the fourth international conference on DV-Xa method (2006) [3]. The difficulty in the application to the semiconductor crystals might be related with a kind of a sea with + electronic charges used in the Madelung potential technique. This is partly so because the semiconductor crystals such as Si and diamond are of covalent bond structure and these crystals are composed of a single element. These two difficulties make the application of a Madelung potential to the semiconductor crystals difficult. 

The electronic structures and chemical bonding of lithium vanadium oxide were calculated by the DV-Xa method [10,11] using the program code [12]. The population analysis was made according to Mulliken [13]. The ab initio total-energy and molecular dynamics program VASP [14-16], based on the density... 

Therefore in the present paper, we report that the energy difference between the singlet ground state and the triplet excited state is more important than the differences among the overlap populations mentioned above. Therefore a new theoretical way to predict the value of the Haldane gap using the DV-Xa method should be discussed. 

Figure 6.1 S03Pt12 cluster models used for the calculation with DV-Xa method, (a)...

The authors thank Prof. K. Oagasawara and Mr. H. Yoshida for the development of the relativistic DV-Xa method code (RSCAT) and offering it to us. 

H. Adachi, Introduction to Quantum Materials Chemistry - Approach with DV-Xa Method, Sankyo Press, Tokyo, 1991. 

Soft X-Ray Absorption Spectral Analysis of Amorphous Carbon and Carbon Black Using the DV-Xa Method Yasuji Muramatsu... 

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. 

We have recently found that some fine structures can be commonly observed in the C K edge X-ray absorption spectra (XAS) of various sputtered amorphous carbon (a-C) films [5,6] and carbon black (CB) [7], To clarify the spectroscopic fine structures from the local-structure and chemical-state point of view, we have compared the XAS of a-C and CB with those of reference compounds, and estimated the local structures of a-C and CB from the spectroscopic analysis using the DV-Xa method. The present paper describes one of the approaches in determining the local structure of carbon materials using the soft X-ray spectroscopy as well as the DV-Xa method. 

Although the complex local structure of carbon materials cannot be easily or completely elucidated by conventional analysis methods, the high-resolution soft X-ray absorption spectroscopy and spectral analysis using the DV-Xa method are promising tools to analyze the local structure. In addition, comparative analysis of carbon materials with reference compounds that have been known their local and molecular structures is a valid approach for elucidating the local structure. 

In the present paper, we describe a reliable XES in the C K and F K-regions of (CF) , and compare the measured X-ray spectra to their density of states (DOS) calculated by the DV-Xa method. 

In the present study, we have built a novel laboratory USXA spectrometer optimized for the 50-150 eV ultra-soft X-ray (USX) region and for the sample mounted horizontally. We examine the Li-K XANES spectral measurements of lithium halides using the USXA spectrometer. The obtained experimental XANES spectra are analyzed using the theoretically calculated spectra from the DV-Xa method. 

The DV-Xa molecular orbital (MO) calculations were performed to analyze the Li-K XANES spectra of lithium halides powder. The computational details of the DV-Xa method have been previously described [10]. In this method, the exchange-correlation interaction, Vxcr between electrons is given by the Slater s Xa potential,... 

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],... 

Molecular orbital calculations of the DME steam reforming and the methane production increased by C02 injection to coal seam was performed by the DV-Xa method. The equation for the wave function i, (r) at a space point r in atomic units is denoted as... 

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. 

August 20, 2007 Byung-Il Kim Masahiko Morinaga DV-Xa 2006 Chairmen The 4th International Conference on DV-Xa Method (DV-Xa 2006) Industrial-Academic Cooperation Symposium and the 19th DV-Xa Annual Meeting... 

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