error while running code to dertermine energy between 2 non-bonded atoms

Gets Around

4:21:37 AM PDT - Thu, Apr 24th 2014

trying to calculate interaction energy between H and O atom(non-bonded interaction energy, not to be confused with OH- ion).

start HO
 title "Hydrogen - Oxygen in aug-cc-pvdz basis set"
 
 geometry units angstrom
   O     -1.874    24.116    62.689
   H      0.878    22.906    65.000
   
 end
 basis
   * library aug-cc-pvdz
 end
 dft
   xc b3lyp
 end
 
 driver
   maxiter 20
 end
  
 task dft energy
 task dft optimize

getting errors with this code like:

......
........
------------------------------------------------------------------------
  no. of electrons and multiplicity not compatible        9
 ------------------------------------------------------------------------
 ------------------------------------------------------------------------
  current input line : 
    20:  task dft energy
 ------------------------------------------------------------------------
 ------------------------------------------------------------------------
 There is an error in the input file
 ------------------------------------------------------------------------
 For more information see the NWChem manual at http://www.emsl.pnl.gov/docs/nwchem/nwchem.html


 For further details see manual section:                                                                                                                                                                                                                                                                
0:0: no. of electrons and multiplicity not compatible:: 9
(rank:0 hostname:abhisek-workstation pid:7086):ARMCI DASSERT fail. armci.c:ARMCI_Error():260 cond:0
  0: ARMCI aborting 0 (0).
  0: ARMCI aborting 0 (0).

I wish I could seriously utilize some help here.
thank you.

Forum Regular

8:51:16 AM PDT - Thu, Apr 24th 2014

Hi Neo,

The DFT module assumes by default that you are performing a closed shell calculation. However, neutral OH has 9 electrons and hence there is no way to make a closed shell wavefunction out of this. Depending on what problem you want to solve you can either add a charge, for example, add

   charge -1

to create an OH-, specify a spin multiplicity, for example,

  dft

  ...

     odft

     mult 2

  end

to tell the code to do an unrestricted doublet DFT calculation. I hope this helps.

Huub

Gets Around

2:52:22 AM PDT - Fri, May 9th 2014
Hello Huub, Thank you for your reply. But I was trying to calculate the DFT energy between non-bonded O-atom and H-atom, not OH- ion. data i have so far for calculation: O -1.874 24.116 62.689 H 0.878 22.906 65.000 distance between O and H: 2.50 angstrom. thank you.

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