[Pw_forum] using ev.x

[udayagiri sai babu]

hi all
i am using ev.x file given in the pw_tools directory to calculate bulk
modulus and lattice parameter values of chromium. i used murnaghan equation
of state to fit my data i got bulk modulus of 256 gpa where as my
experimental  value is 160 gpa but when i used keane equation of state to
fit the same data i got 148 gpa bulk modulus

why is this much variation? which equation of state should i use for cr?
because for vanadium and Ti murnagan euation of state has given reasonable
(<20% error) values of bulk modulus but not for Cr

please give some suggestions
-- 
U.Saibabu
PhD student,
Deformation mechanisms modeling group,
Materials engineering department,
IISc Bangalore,
India.
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