[Pw_forum] Conversion of del(E)/V to P(stress)

[Afshin Arjangmehr]

Dear QE users and developers,

I have a question regarding calculation of elastic constants in metallic
alloys. When I use tstress=.TRUE. to calculate stress alongside total
energy, in -2%<strain<+2% range (elastic region), I expect to have a linear
variation of stress with strain but my results indicate a totally
non-linear correlation.
I use the E/V vs. strain curve to calculate elastic constants and my
results are consistent with experimental reports. Only, the stress part
calculated within pw.x simulation seems to be incorrect. Now:
1- Am I missing anything besides "tsress" in my input file?
2- Would it be correct if I manually convert E/V (delta(Energy)/Volume) to
P(stress)? and if yes, how?

Thank you very much.
Afshin


-- 
With Best Regards
Afshin Arjhangemehr
PhD candidate in Radiation Application
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