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Báo cáo " Calculation of Morse Potential for Diamond Crystals. Applification to Anharmonic Effective Potential "

Analytical expressions for the Morse potential parameters of diamond crystals have been derived. They contain the energy of sublimation, the compressibility and the lattice constant. Numerical calculations have been carried out for Si and Sn, and the results reflect fundamental properties of this potential. The obtained Morse potential parameters have been used for calculation of the anharmonic correlated effective potentials of these crystals in XAFS theory showing clearly anharmonic effects . . | VNU Journal of Science Mathematics - Physics 24 2008 125-131 Calculation of Morse Potential for Diamond Crystals. Applification to Anharmonic Effective Potential Nguyen Van Hung Nguyen Cong Toan Nguyen Bao Trung Ngo Hoang Giang Department of Physics College of Science VNU 334 Nguyen Trai Thanh Xuan Hanoi Vietnam Received 26 June 2008 received in revised form 15 August 2008 Abstract. Analytical expressions for the Morse potential parameters of diamond crystals have been derived. They contain the energy of sublimation the compressibility and the lattice constant. Numerical calculations have been carried out for Si and Sn and the results reflect fundamental properties of this potential. The obtained Morse potential parameters have been used for calculation of the anharmonic correlated effective potentials of these crystals in XAFS theory showing clearly anharmonic effects . 1. Introduction Interatomic anharmonic potential especially Morse potential has been studied widely 1-12 . The parameters of this potential can be extracted from the XAFS X-ray Absorption Fine Structure 11 12 . They are also used to calculate thermodynamic parameters included in these spectra 4-10 . This potential is successfully applied to calculating the quantities involving atomic interaction especially the anharmonic effects contained in XAFS 5-10 which influence on the physical information taken from these spectra. They are also contained in the expressions of equation of state 1 . Therefore calculation of the Morse potential is very actually desired especially in XAFS theory. The calculation of Morse potential has been carried out for fcc bcc 1 22 and hcp 17 22 crystals. The purpose of this work is to develop a method for calculation of Morse potential parameters of Diamond an interesting crystal structure. Analytical expressions for the parameters of this potential have been derived. They contain the energy of sublimation the compressibility and the lattice constant which are known already .