I am a computer science grad and I am working to write an electronic structure calculation program and I am stuck at forming basis functions using 6-31G Basis set for atoms having higher atomic numbers (p,d,f shells).
For example, consider a gaussian g as
g(alpha) = (2*alpha/pi)^(3/4) * exp(-alpha*r^2).
Looking at the Carbon (1s2 2s2 2p2) basis set data for 6-31G basis set
S 6 1.00
SP 3 1.00
0.7868272350D+01 -0.1193324198D+00 0.6899906659D-01
0.1881288540D+01 -0.1608541517D+00 0.3164239610D+00
0.5442492580D+00 0.1143456438D+01 0.7443082909D+00
SP 1 1.00
0.1687144782D+00 0.1000000000D+01 0.1000000000D+01
How many basis functions will carbon have in this case? A simple H2 molecule where each Hydrogen atom has two basis functions as per 6-31G basis set.
S 3 1.00
S 1 1.00
I can write the two basis functions in the form
b1= 0.0334*g(18.73) + 0.2347*g(2.825) + 0.8137*g(0.64);
In a similar manner, how would I go about writing the basis functions for Carbon atom. Any advise would be very helpful as I am stuck in this for couple of days and haven't been able to find any substantial resource for this.