alat (Ang) Etot (eV)
------------------------------
6.12 -1975.526018
6.14 -1975.531451
6.16 -1975.535169
6.18 -1975.53714
6.20 -1975.537384
6.22 -1975.535722
6.24 -1975.5324
6.26 -1975.527514
Your a is somewhere around 6.19
# Equilibrium volume, a.u.^3 : 602.102908
which gives a=8.44a0=4.46A
Andrei's tool cannot make such an error, so I'd expect that you
converted to atomic units incorrectly.
# Bulk modulus, Kbar : 47.134730
GaSb zincblende a=6.09593 Ang, B=57.0 GPa
It is typical for bulk modulus to be about 10% off expt value, plus or
minus depends on GGA or LDA. (But since the lattice constant is wrong
then this number is not correct anyhow).
