Simulating the structure of amorphous Si_0.5C_0.5 using Lin–Harris molecular dynamics

Abstract

We have amorphised Si 0.5 C 0.5 by ab initio generating random networks with the experimental density of 2.75 g/cm 3 . Two types of crystalline supercells were used at the start: one was a diamond-like periodic supercell of 64 atoms, containing 32 carbons and 32 silicons, chemically ordered, amorphised using Fast Structure w , and the other was an fcc crystalline periodic supercell with 108 atoms, 54 carbons and 54 silicons, chemically ordered, amorphised using DMol 3 from the suite in Materials Studio 3.2 w . The amorphisation is made by heating the periodic samples to just below the melting point (the undermelt -quench approach), and then cooling them down to 0 K. Then the structures are relaxed by annealing and quenching, and finally a geometry relaxation is carried out. Our simulations show that Cerius 2w and Materials Studio 3.2 give equivalent results in general: atoms of one kind are almost completely surrounded by the atoms of the other kind. We also find that the two codes lead to total and partial radial distribution functions such that after weighting them with the corresponding experimental structure factors yield curves that are similar and comparable with experiment. Also CZC bonds with an average bond length of 1.35 Å are found.

Structural and Electronic Properties of Cu64Zr36 BMG by ab initio Molecular Dynamics

“…In the present work we applied a variant of a previously used ab initio approach which has been demonstrated to lead to good results for semiconducting amorphous structures [10][11][12] and metallic structures such as amorphous and liquid aluminum [1,13]: the undermelt-quench approach. We report the corresponding total and partial radial (pair) distribution functions (PDFs) in order to study the atomic arrangement in each supercell.…”

Short-range order in ab initio computer generated amorphous and liquid Cu–Zr alloys: A new approach

“…In the present work we have applied two variants of an ab initio process which has demonstrated to lead to good results for semiconducting amorphous structures [21][22][23][24][25][26][27] and metallic structures such as amorphous and liquid aluminum [28,29], the undermelt-quench approach, to generate amorphous and liquid Cu x Zr 100 À x (x ¼64, 50, 36) alloys. We report the corresponding total and partial pair distribution functions (PDF & pPDFs) in order to study the atomic environment in each phase.…”