Title: Anisotropic mechanical and optical response and negative Poissons ratio in Mo2C nanomembranes revealed by first-principles simulations,
Abstract: Transition metal carbides include a wide variety of materials with attractive
properties that are suitable for numerous and diverse applications. Most recent
experimental advance could provide a path toward successful synthesis of
large-area and high-quality ultrathin Mo2C membranes with superconducting
properties. In the present study, we used first-principles density functional
theory calculations to explore the mechanical and optical response of
single-layer and free-standing Mo2C. Uniaxial tensile simulations along the
armchair and zigzag directions were conducted and we found that while the
elastic properties are close along various loading directions, nonlinear
regimes in stress-strain curves are considerably different. We found that Mo2C
sheets present negative Poisson's ratio and thus can be categorized as an
auxetic material. Our simulations also reveal that Mo2C films retain their
metallic electronic characteristic upon the uniaxial loading. We found that for
Mo2C nanomembranes the dielectric function becomes anisotropic along in-plane
and out-of plane directions. Our findings can be useful for the practical
application of Mo2C sheets in nanodevices.