Gaussian Component Orders¶
The order of the individual components can vary between use cases. gau2grid can
produce any resulting order that a user requires. The C version of the code
must be compiled to a given order. The currently supported orders are as
follows.
Cartesian Order¶
gau2grid currently supports both the cca and molden orders. The number
of components per angular momentum can be computed as:
Row Order¶
The cca order iterates over the upper triangular hyper diagonal and has the
following pattern:
S(\(\ell = 0\)): 1
P(\(\ell = 1\)):X,Y,Z
D(\(\ell = 2\)):XX,XY,XZ,YY,YZ,ZZ
F(\(\ell = 3\)):XXX,XXY,XXZ,XYY,XYZ,XZZ,YYY,YYZ,YZZ,ZZZ
Molden Order¶
The molden order is primarily found in a Molden format and only has a
determined values for \(0 \leq \ell < 4\).
S(\(\ell = 0\)): 1
P(\(\ell = 1\)):X,Y,Z
D(\(\ell = 2\)):XX,YY,ZZ,XY,XZ,YZ
F(\(\ell = 3\)):XXX,YYY,ZZZ,XYY,XXY,XXZ,XZZ,YZZ,YYZ,XYZ
Spherical Order¶
gau2grid currently supports both the CCA and gaussian orders. The numnber
of components per angular momentum can be computed as:
CCA Order¶
An industry standard order known as the Common Component Architecture:
S(\(\ell = 0\)): \(Y_0^0\)
P(\(\ell = 1\)): \(Y_1^{-1}\), \(Y_1^{0}\), \(Y_1^{+1}\),
D(\(\ell = 2\)): \(Y_2^{-2}\), \(Y_2^{-1}\), \(Y_2^{0}\), \(Y_2^{+1}\), \(Y_2^{+2}\)
Gaussian Order¶
The gaussian order as used by the Gaussian program:
S(\(\ell = 0\)): \(Y_0^0\)
P(\(\ell = 1\)): \(Y_1^{0}\), \(Y_1^{+1}\), \(Y_1^{-1}\),
D(\(\ell = 2\)): \(Y_2^{0}\), \(Y_2^{+1}\), \(Y_2^{-1}\), \(Y_2^{+2}\), \(Y_2^{-2}\)