You may wish to consult the attached publication by DM Riffe (J. Opt. Soc. Am. B 19, 1092 (2002)).

http://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=2117&context=physics_facpub

Dear Kulwinder,

Attached please find a paper studied the effective mass and electrical and thermal conductivity of Cu2ZnSnS4 and Cu2ZnSnSe4 using DFT. You can use the same keywords used in the study and depicted in the methodology section:

Methods:

The calculations of band structure are carried out with a self consistent scheme by solving Kohn–Sham equations using the full potential linearized augmented plane wave (FP-LAPW) method within the modified Becke Johnson (MBJ) [12]

potential in the framework of density functional theory (DFT) [13] using Wien2k codes [14]. For the transport calculations, non-shifted mesh with 3000 k points are used. The Kmax = 7/RMT (R is the smallest muffin-tin radius and Kmax is the cutoff

for the plane wave) is the convergence parameter in which calculations stabilize and converge in terms of the desired charge e.g. less than 0.001e between steps. The values of other parameters are Gmax = 12 (magnitude of the largest vector in

charge density Fourier expansion or the plane wave cut-off) and muffin-tin radii for Cu2ZnSnS4 (Cu2ZnSnSe4), which is nearly 2.29 (2.38) for Cu, 2.35 (2.46) for Zn, 2.31 (2.44) for Sn and 2.03 (2.11) for S (Se) a.u. The band structure was fitted using the semi classical theory of the Boltzman package [15], in sequence to attain the

thermoelectric properties of Cu2ZnSnS4 (Cu2ZnSnSe4) compounds. In this package the transport properties are rooted in the rigid band approach to conductivity. The other calculated transport properties i.e. Seebeck coefficient, electrical conductivity, thermal conductivity, power factor and resistivity have been calculated verses the temperature.

Hoping this will be helpful,

Rafik