Near transferable phenomenological n-body potentials for noble metals. (1st August 2017)

• Record Type: Journal Article
• Authors: Pontikis, Vassilis; Baldinozzi, Gianguido; Luneville, Laurence; Simeone, David
• Is Part Of: Journal of physics. Volume 29:Number 35(2017)
• Publication Date: 2017-08-01
• Subjects: n-body potentials -- noble metals -- phonons -- point defects -- stacking fault -- surface energy -- thermal expansion; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/aa7766
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: We present a semi-empirical model of cohesion in noble metals with suitable parameters reproducing a selected set of experimental properties of perfect and defective lattices in noble metals. It consists of two short-range, n -body terms accounting respectively for attractive and repulsive interactions, the former deriving from the second moment approximation of the tight-binding scheme and the latter from the gas approximation of the kinetic energy of electrons. The stability of the face centred cubic versus the hexagonal compact stacking is obtained via a long-range, pairwise function of customary use with ionic pseudo-potentials. Lattice dynamics, molecular statics, molecular dynamics and nudged elastic band calculations show that, unlike previous potentials, this cohesion model reproduces and predicts quite accurately thermodynamic properties in noble metals. In particular, computed surface energies, largely underestimated by existing empirical cohesion models, compare favourably with measured values, whereas predicted unstable stacking-fault energy profiles fit almost perfectly ab initio evaluations from the literature. All together the results suggest that this semi-empirical model is nearly transferable.