$useemunfunc

$useemunfunc, $useemupfunc, and $useemufunc are 3 command to activate the field dependent mobility model

$useemunfunc will activate function getmunbyET(ind,Ex,Ey,T,xp,yp)

$useemupfunc will activate function getmupbyET(ind,Ex,Ey,T,xp,yp)

$useemufunc will activate both function getmunbyET(ind,Ex,Ey,T,xp,yp), and function getmupbyET(ind,Ex,Ey,T,xp,yp)

If only electron or hole are activated, the unactivated one will use constant mobility.