Quantum nuclear motion in silicene: Assessing structural and vibrational properties through path-integral simulations

Abstract

This paper explores the interplay between quantum nuclear motion and anharmonicity, which causes nontrivial effects on the structural and dynamical characteristics of silicene, a two-dimensional (2D) allotrope of silicon with interesting electronic and mechanical properties. Employing path-integral molecular dynamics (PIMD) simulations, we investigate the quantum delocalization of nuclei, unraveling its impact on the behavior of silicene at the atomic scale. Our study reveals that this delocalization induces significant deviations in the structural parameters of silicene, influencing in-plane surface area, bond lengths, angles, compressibility, and overall lattice dynamics. Through extensive simulations, we delve into the temperature-dependent behavior between 25 and 1200 K, unveiling the role of quantum nuclear fluctuations in dictating thermal expansion and phonon spectra. The extent of nuclear quantum effects is assessed by comparing results of PIMD simulations using an efficient tight-binding Hamiltonian, with those obtained from classical molecular dynamics simulations. We compare the magnitude of quantum effects in this material with those in other related 2D crystalline solids, such as graphene and SiC monolayers. The observed quantum effects showcase non-negligible deviations from classical predictions, emphasizing the need for accurate quantum treatments in understanding the material's behavior at finite temperatures. At low $T$, the 2D compression modulus of silicene decreases by a 14% due to quantum nuclear motion.

14 pages, 9 figures

References in corpus (23)

• Two and one-dimensional honeycomb structures of silicon and germanium
• Monolayer honeycomb structures of group IV elements and III-V binary compounds
• High-accuracy first-principles determination of the structural, vibrational and thermodynamical properties of diamond, graphite, and derivatives
• The phonon dispersion of graphite revisited
• Group-IV graphene- and graphane-like nanosheets
• First-principles investigation of mechanical properties of silicene, germanene and stanene
• Simulation and understanding of quantum crystals
• Phase diagram of silicon from atomistic simulations
• Monte Carlo study of the frame, fluctuation and internal tensions of fluctuating membranes with fixed area
• Quantum effects in graphene monolayers: Path-integral simulations
• Cyclic Density Functional Theory : A route to the first principles simulation of bending in nanostructures
• Path-integral molecular dynamics simulation of 3C-SiC
• Functionalized few-layer silicene nanosheets: density functional theory on stability, structural, and electronic properties
• Thermal properties of graphene under tensile stress
• Anharmonicity of the acoustic modes of graphene
• Modeling the series of (n x 2) Si-rich reconstructions of beta-SiC(001): a prospective atomic wire?
• Molecular dynamics simulation of melting of finite and infinite size silicene
• Phonon dispersion in two-dimensional solids from atomic probability distributions
• Quantum effects in two-dimensional silicon carbide
• Nuclear quantum effects in graphane
• Elastic properties and mechanical stability of bilayer graphene: Molecular dynamics simulations
• Isotopic effects in structural properties of graphene
• Nuclear quantum effects in structural and elastic properties of cubic silicon carbide