From NWChem
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| 11:50:17 AM PDT - Thu, Oct 24th 2013 |
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Also about bq charges in NWCHEM versus Gaussian
In Gaussian, Specifying Ghost Atoms
An atom with mechanics type Bq (e.g., O-Bq) is set up as a ghost [Macbeth] of the corresponding atom, with its normal basis functions and numerical integration grid points but no nuclear charge or electrons. This requests a counterpoise calculation. Such calculations differ slightly from ones requested with Massage in previous versions of Gaussian in that they include the grid points from the ghost atoms in DFT XC quadrature. The new way is a more consistent superposition correction and also easier to use. Note that counterpoise calculations can also be requested with the Counterpoise keyword.
In nwchem, it appears that bq can be assigned charges as long as sum of total bq charges equals to integer.(http://www.nwchem-sw.org/index.php/Special:AWCforum/st/id1010/error_dft_inpana:_non-integr...).
Can somebody summarize computational cases to apply bq (embedded charges) properly?
Is the following proper way to study the pure electrostatic effects between molecule A and B.
To distinguish electrostatic or polarization effects between A and B, while I replace some atoms in B with bq at the same xyz location but different/same partial charge amount. Then compare the different properties such as charge or vibration freq on molecule A.
Thanks a lot for your comments
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Niri Forum:Admin, Forum:Mod, NWChemDeveloper, bureaucrat, sysop
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Gets Around
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| 3:49:53 PM PDT - Tue, Oct 29th 2013 |
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Hi,
To do this supply the bq charges as follows in the input file
bq
load bqchargesfile
end
where bqchargesfile is a file in the run directory.
The format of the file is
bq x y z charge
...
Make sure you don't use symmetry and use the nocenter option for the geometry block.
This should allow you to calculate the electrostatic effects on a system due to a background field of charges.
Hope this helps.
Best,
-Niri
niri.govind@pnl.gov
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