Effect of three-body forces on the lattice dynamics of noble metals

Abstract

A simple method to generate an effective electron-ion interaction pseudopotential from the energy wave number characteristic obtained by first principles calculations has been suggested. This effective potential has been used, in third order perturbation, to study the effect of three-body forces on the lattice dynamics of noble metals. It is found that three-body forces, in these metals, do play an important role. The inclusion of such three-body forces appreciably improves the agreement between the experimental and theoretical phonon dispersion curves.

Volume variation of Gruneisen parameters offcc transition metals

“…This model was found to be quite useful to compute cold equation of state up to several M bar pressure, the pressure derivatives of elastic constants and other lattice properties of ten transition metals. The model also predicts Debye-Waller factor and mean square displacement of fcc transition metals reasonably well (Vyas et al 2001a).…”

“…It seems from the presently obtained results for Ni, Ag, Au and Rh that these assumptions are not true for these metals. In fact, it has been known that for Ni (Upadhyaya and Prakash 1986) and also for Ag and Au, the three body forces do play an important role in determining phonon frequencies (Vyas et al 2001b). This fact also shows that some of the components of d-electron effects which were assumed to be cancelled by many body force terms, have to be included in the form factor.…”

Study of lattice dynamics and mechanical properties of Pd and Pt using pseudopotential formulism

“…With the help of phonon frequencies, we have computed the temperature variation of Debye-Waller factor and mean square displacement. The Debye-Waller exponent 2W T is directly calculated from computed phonon density of states in the harmonic approximation using the following expression [34],…”

“…The values of θ and λ is required for the experimental determination of Debye-Waller factors. The mean square displacement for different values of temperature is calculated using relation [34],…”