Calculation of first order polynomial modulated by exponential function pair potential parameters of bcc crystals: Application to effective anharmonic interatomic interaction potential

Abstract

Most notable anharmonic pair potential used for predicting thermodynamic properties of crystals is the Morse potential. The parameters of this potential obtained through theoretical and experimental models have been used to predict the effective anharmonic interatomic interaction potential of both cubic metals and diamond crystals to a very high accuracy. In this work, an anharmonic pair potential in form of a first order polynomial modulated by exponential function pair potentialwas modelled and used to calculate the effectiveanharmonic interatomic interaction potential and the lattice force constant in X-ray Absorption Fine Structure (XAFS) for bcc crystals. The values of the parameters of thispair potentialwere fitted into volume per atom and atomic number in each elementary cell, the energy of sublimation, the compressibility and the lattice constant. The results generated by using these parameters to study the anharmonic interatomic effective potential, local force constant in XAFS theory for Fe, W and Mo are found to be in good agreement with experiment, with those of other theories and in particular with those works where the Morse potentials were used.

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