Finite Temperature Properties of NiTi from First Principles Simulations: Structure, Mechanics, and Thermodynamics.

ABSTRACT: We present a procedure to determine temperature-dependent thermodynamic properties of crystalline materials from density functional theory molecular dynamics (DFT-MD). Finite temperature properties (structural, thermal, and mechanical properties) of the phases (ground state monoclinic B33, martensitic B19', and austenitic B2) of the shape memory alloy NiTi are investigated. Fluctuation formulas and numerical derivatives are used to evaluate mechanical and thermal properties. A modified version of thermodynamic upsampling is used to enable simulations with lower DFT convergence thresholds. In addition, a thermodynamic integration expression is developed to compute free energies from isobaric DFT-MD simulations that accounts for volume changes. Structural parameters, elastic constants, volum

SUBMITTER: Haskins JB 

PROVIDER: S-EPMC6476555 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature