  Borophene, an atomically thin, corrugated, crystalline two-dimensional boron
sheet, has been recently synthesized. We investigate mechanical properties and
lattice thermal conductivity of borophene via reactive molecular dynamics
simulations. We performed uniaxial tensile strain simulations at room
temperature along in-plane directions, and found 2D elastic moduli of 188 N/m
and 403 N/m along zigzag and armchair directions, respectively. The anisotropy
is attributed to the buckling of the borophene structure along the zigzag
direction. We also performed non-equilibrium molecular dynamics to calculate
the lattice thermal conductivity. We predict room-temperature lattice thermal
conductivities of $75.9 \pm 5.0$ W/m-K and $147 \pm 7.3$ W/m-K, respectively,
and estimate effective phonon mean free paths of $16.7 \pm 1.7$ nm and $21.4
\pm 1.0$ nm for the zigzag and armchair directions. The anisotropy is
attributed to differences in the density of states of low-frequency phonons,
with lower group velocities and possibly shorten phonon lifetimes along the
zigzag direction. We also observe that when borophene is strained along the
armchair direction there is a significant increase in thermal conductivity
along that direction. Meanwhile, when the sample is strained along the zigzag
direction there is a much smaller increase in thermal conductivity along that
direction. For a strain of 8\% along the armchair direction the thermal
conductivity increases by a factor of 3.5 (~250\%), whereas for the same amount
of strain along the zigzag direction the increase is only by a factor of 1.2
(~20\%). Our predictions are in agreement with recent first principles results,
at a fraction of the computational cost. The simulations shall serve as a guide
for experiments concerning mechanical and thermal properties of borophene and
related 2D materials.
