3
$\begingroup$

I have been making some failed attempts to calculate interaction energy of 2 monomers using a dummy/ghost atom in NWChem6.5.
The code I was using to calculate the interaction energy is:

title 'bond_energy'
start dimer
geometry units angstrom
  N 5.286 28.124 48.085 
  H 5.966 28.410 48.528 
  O 7.110 29.056 50.252 
  C 7.758 28.682 51.230
end
basis "ao basis"
  * library 6-311+g*
  bqN library N 6-311+g*
  bqH library H 6-311+g*
  bqO library O 6-311+g*
  bqC library C 6-311+g*
end
dft
  xc m06-2x
  direct
  grid fine
  iterations 10000
end
bsse
  mon first 1 2
  mon second 3 4
end
task dft energy

However, I'm not being able to replace H atom with a dummy/ghost atom (with no charge) in the calculation.
If I use bqH 5.966 28.410 48.528 in the geometry section and calculate odft then also the calculation an error.
Any suggestions or modification needed in the code to achieve this target will be highly appreciated.
Thank you.

$\endgroup$
  • $\begingroup$ You should start by just copy-and-pasting the example using their BSSE correction example here. If not, you can just do the BSSE correction by hand by specifying the ghost atoms in the script and giving a task directive below each geometry. $\endgroup$ – jheindel May 8 '18 at 7:38
  • $\begingroup$ I don't want to do that. I want to calculate the bsse energy of NHOC bond, in absence of H atom. That's why I'm trying to replace it with dummy atom. $\endgroup$ – diffracteD May 11 '18 at 8:11
  • 1
    $\begingroup$ Using the notation @ for a ghost atom, does this mean you want the BSSE of $\ce{N@H\bond{...}OC}$? That is, keep the hydrogen as a ghost atom during all 5 parts of the BSSE calculation? If so, you may have to do the whole thing "by hand" and piece the BSSE expression together manually, otherwise the program will try and replace a ghost atom with a ghost atom, which is an edge case. $\endgroup$ – pentavalentcarbon May 12 '18 at 16:06
  • 1
    $\begingroup$ Something else that's missing: what do you expect the charge and spin multiplicity to be on each of your fragments? $\endgroup$ – pentavalentcarbon May 12 '18 at 16:07
  • $\begingroup$ Sorry, 3 calculations, not 5. (AB in the basis of AB) - [(A in the basis of AB) + (B in the basis of AB)], all with ghost H. $\endgroup$ – pentavalentcarbon May 12 '18 at 16:27

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.