Interaction potential for silicon carbide: A molecular dynamics study of elastic constants and vibrational density of states for crystalline and amorphous silicon carbide

Abstract

An effective interatomic interaction potential for SiC is proposed. The potential consists of two-body and three-body covalent interactions. The two-body potential includes steric repulsions due to atomic sizes, Coulomb interactions resulting from charge transfer between atoms, charge-induced dipole-interactions due to the electronic polarizability of ions, and induced dipole-dipole ͑van der Waals͒ interactions. The covalent characters of the Si-C-Si and C-Si-C bonds are described by the three-body potential. The proposed three-body interaction potential is a modification of the Stillinger-Weber form proposed to describe Si. Using the molecular dynamics method, the interaction potential is used to study structural, elastic, and dynamical properties of crystalline ͑3C͒, amorphous, and liquid states of SiC for several densities and temperatures. The structural energy for cubic ͑3C͒ structure has the lowest energy, followed by the wurtzite ͑2H͒ and rock-salt ͑RS͒ structures. The pressure for the structural transformation from 3C-to-RS from the common tangent is found to be 90 GPa. For 3C-SiC, our computed elastic constants ͑C 11 , C 12 , and C 44 ͒, melting temperature, vibrational density-of-states, and specific heat agree well with the experiments. Predictions are made for the elastic constant as a function of density for the crystalline and amorphous phase. Structural correlations, such as pair distribution function and neutron and x-ray static structure factors are calculated for the amorphous and liquid state.

Influence of microstructures on mechanical behaviours of SiC nanowires: a molecular dynamics study

“…Parameters used in the interaction potential for SiC NWs, as shown in equations (1)- (6), where λ = 5.0Å, ξ = 3.0Å and r c = 7.35Å [25]. The effective charge on Si and C are 1.201e and −1.201e, respectively (e being the unit of electronic charge).…”

“…The parameter values of these two-body and three-body potentials are listed in table 1 [25]. The motion of atoms is integrated using a Verlet leapfrog algorithm to yield velocities and positions with a time step of 2 fs.…”

Mechanically induced stiffening, thermally driven softening, and brittle nature of SiC

“…Previous high pressure experimental [3,4] and theoretical [5][6][7][8][9][10][11][12][13][14][15] research of SiC infers cubic (3C), hexagonal (6H), and rhombohedral (15R) structures. Energy-dispersive X-ray diffraction with a diamond anvil cell shows a structural transition from zinc blende (ZB, B3) to rock salt (RS, B1) at 100 GPa with a volume collapse of about 20.3% [3].…”

“…The molecular dynamics with effective interatomic interaction potential for SiC incorporating two-body and three-body covalent interactions is also proposed [15,16]. The covalent characteristic SiC is described by the three-body potential using modified Stillinger-Weber form.…”

“…The covalent characteristic SiC is described by the three-body potential using modified Stillinger-Weber form. The molecular dynamics method with the developed interaction potential is employed to investigate the structural, elastic, and dynamical properties of crystalline 3C, amorphous, and liquid states of SiC for several densities and temperatures [15,16]. The quantum mechanical calculations are powerful probes to generate reference data for the experimentalists and to tailor new structures of materials [17].…”