| 12:46:03 PM PDT - Fri, Sep 28th 2012 |
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I think to get what you really want will require you to modify the code.
Effectively, what ESP does it generates a grid and then looks at the nuclear and electronic contributions to the electrostatic potential at each point on the grid. Then it tries to fit charges on the atom position that represent this potential.
The trick I though of below effectively generates a electrostatic potential with the nuclear component from the atoms closer to each other plus the electronic contribution from the atoms further away.
What you will have to do in the code is to have the code generate the electrostatic potential on the grid using the original geometry, and then only in the fitting part adjust the atom positions to where you want to calculate the partial charges.
Still not clear what it will mean as the electron density assumes the atomic charge in one location and how you move that charge away.
Bert
Quote:P99 Sep 28th 1:15 pmUnfortunately, this is not working.
1) Problem is that the program automatically moves the coordinates.
I solved it with words “nocenter noautosym”.
2) For the first time “task esp” gives the correct dipole moment, but in the second case (with the new geometry) both dipole and partial charges are greatly reduced.
In fact, the dipole moment should remain near the same by increasing the partial charges.
start nw
geometry nocenter noautosym
F 0.0 0.0 0.0883587
H 0.0 0.0 -0.8331587
end
basis spherical
* library aug-cc-pvdz
end
esp
recalculate
probe 0.07
range 0.3
factor 1
spacing 0.02
end
mp2
tight
freeze atomic
end
task MP2 gradient
set "esp:input vectors" nw.mp2nos
task esp
geometry nocenter noautosym
F 0.0 0.0 0.
H 0.0 0.0 -0.8331587
end
task esp
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