[CP2K:5421] Binding energy of graphene bilayer: CHARMM vs. DFT-D3

[hut... at chem.uzh.ch]

Hi

- first question: What is the value given in literature?
  I'm sure there are others that have calculated this.

- Are your values based on a single geometry (and stacking) or
  did you optimize geometry and cell size?

- Your relative cutoff is rather low (25).

Without further information we don't know where to look for 
a problem.

regards

Juerg 
--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Institut für Chemie C                FAX   : ++41 44 635 6838
Universität Zürich                   E-mail: hut... at chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

-----cp... at googlegroups.com wrote: -----
To: cp... at googlegroups.com
From: Robert Yang 
Sent by: cp... at googlegroups.com
Date: 06/18/2014 09:24PM
Subject: [CP2K:5421] Binding energy of graphene bilayer: CHARMM vs. DFT-D3

Dear all,

I am calculating the binding energy of graphene bilayer of the size 3nmX3nm (2X416 atoms). It turns out that the result from calculations with classical force field is quite different from that of DFTs:

CHARMM FF:                                       -0.579 Hartree
DFT-D3:                                                -1.056 Hartree
DFT-D3 with BSSE correction:           -0.968 Hartree

It is quite strange that the value of CHARMM is nearly one half of DFT results. 

The binding energy is defined here as: dE = E_bilayer - 2*E_single_layer.

All my input files are attached in the tar file. Please help me to find out where the problem lies in. Thank you!

Best wishes,
Robert
  
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[attachment "t.tar" removed by Jürg Hutter/at/UZH]