$negfacousticphonon

$negfacousticphonon is the command to setup the related parameters of acoustic phonon scattering.
The equation of acoustic phonon scattering:

$W_{ac}(k)=\frac{2\pi k_{B}T}{\hbar\rho\nu_{ac}^{2}}D_{ac}I_{if}N_{1D}(E_{k})$

Example:

$negfacousticphonon
$D_{ac}$ $\nu_{ac}$

$negfacousticphonon
1.248e-18 5.22e3
# Dac vac