# CCL:G: Defining quadrupole in Gaussian 03

*From*: "Andrew Joseph Adamczyk"
<a-adamczyk:+:northwestern.edu>
*Subject*: CCL:G: Defining quadrupole in Gaussian 03
*Date*: Fri, 18 May 2007 13:12:56 -0400

Sent to CCL by: "Andrew Joseph Adamczyk"
[a-adamczyk]=[northwestern.edu]
Hello Everyone,
Ultimately I want to assign the charges for the quadrupole moment in N2 against
the bias in Gaussian described below (or perhaps persuade against the bias).
That is, I am able to generate the quadrupole tensor which has nonzero
components Qxx, Qyy, and Qzz. The latter of which is the calculated quadrupole
moment for N2. This is with the bias that the quadrupole is of -++-
conformation.
I also ran the pop=chelpg option and received the following output which only
constrains the dipole moment giving zero partial charges:
Breneman (CHELPG) radii used.
Generate Potential Derived Charges using the Breneman model, NDens= 1.
Grid spacing= 0.300 Box extension= 2.800
NStep X,Y,Z= 20 20 24 Total possible points= 9600
Number of Points to Fit= 3328
**********************************************************************
Electrostatic Properties Using The SCF Density
**********************************************************************
Atomic Center 1 is at 0.000000 0.000000 0.554640
Atomic Center 2 is at 0.000000 0.000000 -0.554640
3328 points will be used for fitting atomic charges Fitting point charges
to eletrostatic potential
Charges from ESP fit, RMS= 0.00536 RRMS= 1.00000:
Charge= 0.00000 Dipole= 0.0000 0.0000 0.0000 Tot= 0.0000
1
1 N 0.000000
2 N 0.000000
If anyone is able to manipulate Gaussian to allow for unique quadrupole
arrangements (with point charges perhaps) in an effort to generate the
electrostatic potential surface, your suggestions would be greatly appreciated.
Thank you in advance.