A comparison of methods for melting point calculation using molecular dynamics simulations

Abstract

Accurate and efficient prediction of melting points for complex molecules is still a challenging task for molecular simulation, although many methods have been developed. Four melting point computational methods, including one free energy-based method (the pseudo-supercritical path (PSCP) method) and three direct methods (two interface-based methods and the voids method) were applied to argon and a widely studied ionic liquid 1-n-butyl-3-methylimidazolium chloride ([BMIM][Cl]). The performance of each method was compared systematically. All the methods under study reproduce the argon experimental melting point with reasonable accuracy. For [BMIM][Cl], the melting point was computed to be 320 K using a revised PSCP procedure, which agrees with the experimental value 337-339 K very well. However, large errors were observed in the computed results using the direct methods, suggesting that these methods are inappropriate for large molecules with sluggish dynamics. The strengths and weaknesses of each method are discussed.

An interaction potential for barium sulfide: A molecular dynamics study

“…The exact determination of the melting point by molecular dynamics methods is not a simple task [35]. Here, two methods were used to estimate the melting temperature: homogeneous melting temperature [35,36], based on mechanical melting, and the phase coexistence method [37,38].…”

“…Here, two methods were used to estimate the melting temperature: homogeneous melting temperature [35,36], based on mechanical melting, and the phase coexistence method [37,38]. The mechanical melting was determined by using the schedule discussed above.…”

Configurational mapping significantly increases the efficiency of solid-solid phase coexistence calculations via molecular dynamics: Determining the FCC-HCP coexistence line of Lennard-Jones particles

“…The reference Gibbs free energy difference value is determined using the pseudo-supercritical path method [43][44][45] (PSCP). This method determines the free energy required to take each polymorph from a real crystal to an ideal gas; the free energy between the two polymorphs is then the difference of those values.…”

Using reweighting and free energy surface interpolation to predict solid-solid phase diagrams

“…In order to obtain a ∆G value between each set of polymorphs, the reduced free energy values within polymorphs obtained by MBAR must be combined with a reference Gibbs free energy difference between polymorphs at the same T and P . While the reference free energy can be obtained using a variety of methods, such as metadynamics 41,42 and the Frenkel-Ladd method 43 , here the reference free energy difference is calculated using a pseudo-supercritical path (PSCP) 34,37,44 . The reference free energy must be at a point where the less-stable phase is kinetically trapped, which can generally be a moderate distance from the phase equilibrium line for solid-solid equilibria, and often for liquid-solid equilibria as well.…”