Ideal strength and phonon instability of strained monolayer materials

Abstract

The ideal strength of monolayer materials possessing semimetallic, semiconducting, and insulating ground states is computed using density functional theory. Here we show that, as in graphene, a soft mode occurs at the K-point in BN, graphane, and MoS${}_2$, while not in silicene. The transition is first-order in all cases except graphene. In BN and graphane the soft mode corresponds to a Kekul{é}-like distortion similar to that of graphene, while MoS${}_2$ has a distinct distortion. The phase transitions for BN, graphane, and MoS${}_2$ are not associated with the opening of a band gap, which indicates that Fermi surface nesting is not the driving force. We perform an energy decomposition that demonstrates why the soft modes at the K-point are unique and how strain drives the phonon instability.

References in corpus (5)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Fermi surface nesting and the origin of Charge Density Waves in metals
• Electron fractionalization in two-dimensional graphenelike structures
• Electronic Strengthening of Graphene by Charge Doping
• Ideal Strength of Doped Graphene

Cited by in corpus (6)

• Strain engineering in semiconducting two-dimensional crystals
• Colloquium: Hydrodynamics and holography of charge density wave phases
• Strain Effects on the Mechanical Properties of Group-V Monolayers with Buckled Honeycomb Structures
• Elasticity bounds from Effective Field Theory
• Strain effects in monolayer Iron-Chalcogenide superconductors
• Mechanical stability of homogeneous holographic solids under finite shear strain