Boiling point determination using adiabatic Gibbs ensemble Monte Carlo simulations: Application to metals described by embedded-atom potentials

Abstract

The normal boiling points are obtained for a series of metals as described by the "quantum-corrected Sutton Chen" (qSC) potentials [S.-N. Luo, T. J. Ahrens, T. Çağın, A. Strachan, W. A. Goddard III, and D. C. Swift, Phys. Rev. B 68, 134206 (2003)]. Instead of conventional Monte Carlo simulations in an isothermal or expanded ensemble, simulations were done in the constant-NPH adabatic variant of the Gibbs ensemble technique as proposed by Kristóf and Liszi [Chem. Phys. Lett. 261, 620 (1996)]. This simulation technique is shown to be a precise tool for direct calculation of boiling temperatures in high-boiling fluids, with results that are almost completely insensitive to system size or other arbitrary parameters as long as the potential truncation is handled correctly. Results obtained were validated using conventional NVT-Gibbs ensemble Monte Carlo simulations. The qSC predictions for boiling temperatures are found to be reasonably accurate, but substantially underestimate the enthalpies of vaporization in all cases. This appears to be largely due to the systematic overestimation of dimer binding energies by this family of potentials, which leads to an unsatisfactory description of the vapor phase.

Scaling Laws and Critical Properties for fcc and hcp Metals

“…In this work, we use the quantum-corrected Sutton–Chen embedded atoms (qSC-EAM) potential. The qSC-EAM potential has been shown to accurately describe thermodynamic properties of liquid metals, − as well as the boiling points of metals and the vapor–liquid equilibrium properties of Copper. , In the qSC-EAM potential, the potential energy U of a system containing N atoms is written as the sum of a contribution of a two-body term and a contribution of a many-body term in which r ij is the distance between two atoms i and j and the density term ρ i is given by We use the parameters of Luo et al for the 11 fcc and hcp metals (Ag, Al, Au, Be, Cu, Ir, Ni, Pb, Pd, Pt, and Rh) studied in this work. The interaction between a fractional atom and a full atom is given by eqs and using the scaled paramters a l = a ( l / M ) 1/4 instead of a and C l = C ( l / M ) 1/3 instead of C where l is the current stage value of the fractional particle (0 < l < M – 1).…”

“…In this work, we use the quantum-corrected Sutton− Chen 36 embedded atoms (qSC-EAM) potential. The qSC-EAM potential has been shown to accurately describe thermodynamic properties of liquid metals, 36−44 as well as the boiling points of metals 45 and the vapor−liquid equilibrium properties of Copper. 46,47 In the qSC-EAM potential, the potential energy U of a system containing N atoms is written as the sum of a contribution of a two-body term and a contribution of a many-body term…”

“…The aim of this work is to use molecular simulation to determine the critical properties of a series of fcc and hcp metals modeled with a many-body force field known as the quantum-corrected Sutton–Chen potential . This model was shown to accurately model the properties of liquid metals, − as well as the boiling points of metals and the vapor–liquid equilibrium properties of Cu. , To determine the vapor–liquid properties, as well as the locus of the Zeno line, we use the recently developed expanded Wang–Landau simulation method. − This method leads to an accurate determination of the grand-canonical partition function of a system, and in turn, to all thermodynamic properties, including the vapor and liquid densities at coexistence and the compressibility factor. This allows us to determine the Zeno line, the Boyle parameters, and the critical point for all metallic systems studied in this work.…”

“…28−35 The aim of this work is to use molecular simulation to determine the critical properties of a series of fcc and hcp metals modeled with a many-body force field known as the quantum-corrected Sutton−Chen potential. 36 This model was shown to accurately model the properties of liquid metals, 36−44 as well as the boiling points of metals 45 and the vapor−liquid equilibrium properties of Cu. 46,47 To determine the vapor− liquid properties, as well as the locus of the Zeno line, we use the recently developed expanded Wang−Landau simulation method.…”

The central role of entropy in adiabatic ensembles and its application to phase transitions in the grand-isobaric adiabatic ensemble

“…We model Cu, and the many-body interactions that take place in this metal, with an embedded-atom potential (EAM) [36][37][38][39] known as the quantum-corrected Sutton-Chen 40 embedded atoms (qSC-EAM) potential. The qSC-EAM potential is a density-dependent force fields that has been shown to be very versatile, as it models accurately the thermodynamic and transport properties of liquid metals [40][41][42][43][44][45][46] , as well as their boiling points 47,48 . According to this force field, the potential energy U of a system containing N atoms is equal to the sum of a two-body term and of a many-body term…”