yambo calculate the exciton lifetime

[Jagjit Kaur]

Dear all,

I was trying to calculate the exciton lifetime of a 3D material using the following formula:

radiative decay rate = \frac{8\sqrt{\pi\epsilon}e^2\hbar p_{s}^{2}}{3\epsilon_0 m^2 V E_s(0)^2}(\frac{E_s(0)^2}{2M_s m c^2k_BT})^{3/2}, and the excitonic lifetime is inverse of radiative decay rate.

Here, e is electron charge 1.60217663 × 10-19C, m is electron mass is 9.1093837 × 10-31 kg, \epsilon_0 is permitivity in vaccuum is 8.8541878128×10−12, k_B is boltzmann constant which is 8.617333262×10−5eV/K, \hbar is planck's constant which is 6.652119x10^-16 eVs, c is speed of light which is 3x10^8 m/s, T is temperature which is 300K, \pi is 22/7. \epsilon which is dielectric constant is unitless, p_{s}^{2} which is oscillator strength in units of eV, E_s(0) which is exciton energy in unit of eV, M_s which is exciton effective mass in the units of electron rest mass energy, V is the volume of the material in m^3

I am getting the lifetime in the order of e-55 ps which is too less. Basically the order of lifetime is coming out to be wrong.

Can the yambo community help me whether the units and the values of different parameters are correct?

Regards