[Pw_forum] Intermolecular energy of two fragments.

[Valentina Cantatore]

Good morning to everyone.

I would like to calculate the interaction energy between to molecules using
QE. What I set up was to fix the dimension of a cubic box at 20 A (I think
it is big enough to avoid interactions between the other replicated
molecules), calculate the energy of each of the two fragments (Ea and Eb)
and then calculate the energy of the two fragments together (Eab). What I
expect is that interaction energy (Ein) is given by Ein=Eab-(Ea+Eb).

I also used the assume_isolated option for all calculations. I sampled only
gamma points.

The results obtained are not of the same order of magnitude of those
obtained with a gaussian basis set on the same systems.

Where am I wrong? Is it possible run this kind of calculation with Quantum
Espresso? Thank you

Valentina Cantatore
PostDoc Researcher @ Università del Piemonte Orientale
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