Development of RF-MEAM interatomic potentials for high temperature diborides

Reference free (RF) MEAM interatomic potentials have been developed to investigate the thermodynamic stability and thermo-mechanical properties of ultra-high temperature binary including ZrB2 and entropy-stabilized diborides by fitting the energy, forces, stress obtained from the DFT datasets including lattice deformations and high-temperature NVT ab-initio ensembles. The fitting technique implements a conjugate gradient minimizer along with Genetic Algorithm (GA) using the MEAMfit code. A few critical materials properties of the diborides including the bulk modulus, elastic constants, cohesive and point defect energy were calculated and compared with the experimental and DFT results to verify the interatomic potentials. In addition, the vibrational characteristics of these compounds were calculated to elucidate their experimentally observed thermal expansion and thermal conductivity at ultra-high temperatures. The support from CMMI Division of NSF (Award No. 1902069) is gratefully acknowledged.