  We perform classical molecular dynamics to investigate the effects of
mechanical strain on single-layer black phosphorus nanoresonators at different
temperatures. We find that the resonant frequency is highly anisotropic in
black phosphorus due to its intrinsic puckered configuration, and that the
quality factor in the armchair direction is higher than in the zigzag direction
at room temperature. The quality factors are also found to be intrinsically
larger than graphene and MoS2 nanoresonators. The quality factors can be
increased by more than a factor of two by applying tensile strain, with
uniaxial strain in the armchair direction being most effective. However, there
is an upper bound for the quality factor increase due to nonlinear effects at
large strains, after which the quality factor decreases. The tension induced
nonlinear effect is stronger along the zigzag direction, resulting in a smaller
maximum strain for quality factor enhancement.
