In this work, the X-ray absorption fine structure (XAFS) spectra of bcc crystals and their Fourier transform magnitudes have been studied based on the anharmonic correlated Debye model high-order expanded Debye-Waller factors. The many-body effects are taken into account in present one-dimensional model based on the anharmonic effective potential that includes interactions of absorber and backscatterer atoms with their first shell near neighbors, where the Morse potential is assumed to describe the single-pair atomic interaction. | Communications in Physics, Vol. 27, No. 1 (2017), pp. 55-64 DOI: X-RAY ABSORPTION FINE STRUCTURE OF BCC CRYSTALS STUDIED BASED ON HIGH-ORDER EXPANDED DEBYE-WALLER FACTORS NGUYEN VAN HUNG1,† , TRINH THI HUE1 , HA DANG KHOA2 AND TONG SY TIEN3 1 Department of Physics, Hanoi University of Science. 334 Nguyen Trai, Thanh Xuan, Hanoi, Vietnam 2 School of Engineering Physics, Hanoi University of Science and Technology, 1 Dai Co Viet, Hai Ba Trung, Hanoi, Vietnam 3 Department of Basic Sciences, University of Fire Fighting & Prevention, 243 Khuat Duy Tien, Thanh Xuan, Hanoi, Vietnam † E-mail: hungnv@ Received 24 November 2016 Accepted for publication 30 March 2017 Abstract. In this work, the X-ray absorption fine structure (XAFS) spectra of bcc crystals and their Fourier transform magnitudes have been studied based on the anharmonic correlated Debye model high-order expanded Debye-Waller factors. The many-body effects are taken into account in present one-dimensional model based on the anharmonic effective potential that includes interactions of absorber and backscatterer atoms with their first shell near neighbors, where the Morse potential is assumed to describe the single-pair atomic interaction. Analytical expressions of four first temperature-dependent cumulants of bcc crystals have been derived using the manybody perturbation approach. The obtained cumulants are applied to calculating XAFS spectra and their Fourier transform magnitudes. Numerical results for bcc phase of Fe are found to be in good agreement with the experimental data. Keywords: Debye-Waller factor, effective potential, correlated Debye model, XAFS, bcc crystals. Classification numbers: , , . I. INTRODUCTION The X-ray Absorption Fine Structure (XAFS) spectra have developed into a powerful technique for providing information on the local atomic structure and thermal effects of substances [1– 20]. The formalism for including anharmonic .
