[Pw_forum] equivalent supercells, vdW, stresses

Niels R. Walet Niels.Walet at manchester.ac.uk
Wed Sep 2 12:48:53 CEST 2015

Dear Stefano,

> are you sure the two cells are equivalent?

that is a great question--I am no longer as sure as I was before. 
Visually they look incredibly similar--but I am doing all possible 
checks (turning of vdW, dipole, and other corrections). Why the energies 
would be the same up to the 0.2meV /molecule level is not yet clear to me.

>In your message you say the in-plane stresses are different, and in the
>subsequent line you say they are equal... What exactly is different and
>what is equal?

What I mean is they differ for the two calculations, but there are two in-plane stresses, which are equal for each calculation (which meand shap optimisation has worked correctly).

Prof. Niels R. Walet                   Phone:  +44(0)1613063693
School of Physics and Astronomy        Fax:    +44(0)1613064303
The University of Manchester           Mobile: +44(0)7905438934
Manchester, M13 9PL,  UK               room 7.7, Schuster Building
email: Niels.Walet at manchester.ac.uk
web:   http://www.theory.physics.manchester.ac.uk/~mccsnrw

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