Abstract
We apply the efficient two-optimized references thermodynamic integration using Langevin dynamics method [Phys. Rev. B 96, 224202 (2017)] to calculate highly accurate melting properties of Al and magnetic Ni from first principles. For Ni we carefully investigate the impact of magnetism on the liquid and solid free energies including longitudinal spin fluctuations and the reverse influence of atomic vibrations on magnetic properties. We show that magnetic fluctuations are effectively canceling out for both phases and are thus not altering the predicted melting temperature. For both elements, the generalized gradient approximation (GGA) and the local-density approximation (LDA) are used for the exchange-correlation functional revealing a reliable ab initio confidence interval capturing the respective experimental melting point, enthalpy of fusion, and entropy of fusion.
Highlights
Melting points, T m, of materials have always been an important topic in materials science
The critical feature of twostage up-sampled thermodynamic integration using Langevin dynamics (TU-TILD) is that the reference potential—for which an embedded atom method (EAM) parametrization was used in the original work—is fitted to a set of density functional theory (DFT) molecular dynamics (MD) energies so that it reproduces the ab initio system very closely at finite temperatures
We have recently proposed the two-optimized references thermodynamic integration using Langevin dynamics (TOR-TILD) methodology [7] for melting property calculations, in which a second optimized reference potential is fitted to DFT MD energies of the liquid phase
Summary
T m, of materials have always been an important topic in materials science. The critical feature of TU-TILD is that the reference potential—for which an embedded atom method (EAM) parametrization was used in the original work—is fitted to a set of DFT MD energies so that it reproduces the ab initio system very closely at finite temperatures. Extending this idea, we have recently proposed the two-optimized references thermodynamic integration using Langevin dynamics (TOR-TILD) methodology [7] for melting property calculations, in which a second optimized reference potential is fitted to DFT MD energies of the liquid phase.
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