[Wien] specific heat factor

[jan kunes]

There is the electronic specific heat C_v/T, which is for non-interacting 
electrons propotional to the density of states at Fermi level, printed out
in the output of tetra. I find the convesion factor from N(E_F) in 1/Ry
to gamma in mJ/(K^2 mol) strange:

gamma=N(E_F)/2.d0*(8.617D-5)**2*(pi**2)/3.d0*2.6255D6/27.212d0*1000.d0

does anybody know where the 2.6255D6 comes from? By the way conversion 
factor I normally use is gamma[mJ/K^2/mol]=0.173*N(E_F)[1/Ry] (quite 
different from wien value).

Jan Kunes