[Pw_forum] Rydberg to KJ/mole

[Guntram Schmidt]

Dear Paolo,

that's why, I only quoted and argued on energy differences.

However, they seem to be too far away from expectation (10-fold).

Is there any normalisation to be made? Dividing by the number of 
molecules per unit cell (if there is one per asymmetric unit, this would 
refer to 8 for an orthorombic case, e.g.)?

I'm not sure, what the "reference" of the calculated Rydberg value is - 
if it would be the whole cell, I would get doubled energy values and 
differences when I calculate a 2x1x1 supercell...

The other way round: what does "per mole" really mean in a conversion of 
"some amount" to "a mole" (e.g.: Joule to Joule/mol)...

Thanks for helping me!


Am 21.03.2012 19:14, schrieb Paolo Giannozzi:
>
> On Mar 21, 2012, at 17:05 , Alex Kutana wrote:
>
>> There is a search function for the pw_forum, although It's well hidden
>
> there are two search functions, both linked and well visible in the
> "Contacts" page of the QE web site.
>
> About the original qeustion: QE calculates total energies per unit cell,
> in Ry. The absolute value of the energy depends upon the specific
> set of pseudoppotential and has no physical meaning; energy differences
> have physical meaning
>
> P.
> ---
> Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
>
>
>