Development of a modified embedded atom classical interatomic potential for ternary transition metal nitrides
||Development of a modified embedded atom classical interatomic potential for ternary transition metal nitrides|
||Kostas Sarakinos <email@example.com>|
||2015-09-21 – 2020-12-01|
The aim of the current project is the development of a modified embedded atom (MEAM) classical interatomic potential for the Ti-Al-N system. The development of this potential will allow us to perform large scale MD simulations, and thereby investigate for the first time the behaviour of this system during the thin film growth at an atomic level.
Complex electronic configuration of the transition metal nitrides, the metal - non-metal bonds and the multitude structural configurations and phases of the binaries Al-N and Ti-Al make the particular ternary alloy a challenging system for study with MD simulations. Simple semi-empirical potentials have been proven inadequate for working with transition metal nitrides in the past, while MEAM potentials have been successfully used for study of binary metal nitrides. This is the reason why MEAM seems as the best candidate potential scheme for use with these systems.
Due to lack of Al-N and Ti-Al MEAM potentials in literature, the first step towards the parameterization of the ternary system will be the parameterization of the three involved binary systems, i.e., Ti-N, Al-N and Ti-Al. Only then, every possible stable or metastable phase during the thin film growth will be effectively predicted.
The parameterization procedure will be handled by a Metropolis Monte Carlo code which will scan the parameter space trying to find which MEAM parameters are resulting in the best fit, to literature data of various physical properties of the material system in question. The parameter sets with the best fits will be further tested in long scale simulations.
Considering the aforementioned complexity of the particular system and the parameterization procedure, in addition with the complicate formalism of the MEAM potentials which may include up to 40 depended adjustable parameters for a ternary alloy, a substantial large number of long calculations is demanded. According to previously gained experience, it will be needed several months of full day calculations at more than 100 processors in order to achieve decent fittings for a complex binary system.