I was trying lately to calculate by hand the number of basis functions and primitive gaussians for CH4 using Pople's split-valence basis sets, namely 6-31G, 6-31G(d) and 6-31g(d,p) and compare my results to Gaussian09 output.
And when it comes to the two first basis - my calculations seem to be in prefect agreement with computer ones (6-31G: 17 basis functions, 38 primitive gaussians; 6-31G(d): 23 basis functions, 44 primitive gaussians) but for the 6-31G(d,p) basis according to my point of view thare's only 34 basis functions and 55 primitive gaussians. Gaussian output suggests however that it should be 35 basis functions and 56 primitve gaussians. Could someone find where I'm losing that additional function and which factors I'm not taking into account? I'm working with default (6d,7f) way of handling higher orbitals.
My way of thinking:
C:
1s (core) - 1 contraction (6 prim. gauss) + 1 extra P-function ['contraction' of 1 prim. gauss.] [a bit far-fetched for me but because of (d,P)(?); the same for 2s]
2s (valence) - 1 contraction (3 prim. gauss) + 1 extra P-function ['contraction' of 1 prim. gauss.] , 1 'contraction' (1 prim. gauss) + 1 extra P-function ['contraction' of 1 prim. gauss.]
2px (valence) - 1 contraction (3 prim. gauss) + 1 extra D-function ['contraction' of 1 prim. gauss.], 1 'contraction' (1 prim. gauss) + 1 extra D-function ['contraction' of 1 prim. gauss.]
2py (valence) - 1 contraction (3 prim. gauss) + 1 extra D-function ['contraction' of 1 prim. gauss.], 1 'contraction' (1 prim. gauss) + 1 extra D-function ['contraction' of 1 prim. gauss.]
2pz (valence) - 1 contraction (3 prim. gauss) + 1 extra D-function ['contraction' of 1 prim. gauss.], 1 'contraction' (1 prim. gauss) + 1 extra D-function ['contraction' of 1 prim. gauss.]
TOTAL - 18 basis functions; 31 primitive gaussians
H(1):
1s (valence) - 1 contraction (3 prim. gauss) + 1 extra P-function ['contraction' of 1 prim. gauss.], 1 'contraction' (1 prim. gauss) + 1 extra P-function ['contraction' of 1 prim. gauss.]
H(2):
1s (valence) - 1 contraction (3 prim. gauss) + 1 extra P-function ['contraction' of 1 prim. gauss.], 1 'contraction' (1 prim. gauss) + 1 extra P-function ['contraction' of 1 prim. gauss.]
H(3):
1s (valence) - 1 contraction (3 prim. gauss) + 1 extra P-function ['contraction' of 1 prim. gauss.], 1 'contraction' (1 prim. gauss) + 1 extra P-function ['contraction' of 1 prim. gauss.]
H(4):
1s (valence) - 1 contraction (3 prim. gauss) + 1 extra P-function ['contraction' of 1 prim. gauss.], 1 'contraction' (1 prim. gauss) + 1 extra P-function ['contraction' of 1 prim. gauss.]
TOTAL - 16 basis functions; 24 primitive gaussians
Altogether - 34 basis functions; 55 primitive gaussians