Ab initio calculated symmetry coordinate and internal valence coordinate coefficients for the two spin-spin coupling surfaces of the silane molecule-(1)J(Si, H) and (2)J(H,H)-are presented. Calculations were carried out at the level of the second-order polarization propagator approximation involving coupled-cluster singles and doubles amplitudes [SOPPA(CCSD)] using a large basis set for a total of 78 different geometries corresponding to 133 distinct points on the (1)J(Si, H) surface and 177 distinct points on the (2)J(H,H) surface. The results were fitted to fourth order in Taylor series expansions and are presented to second order in the coordinates. Both couplings are sensitive to geometry-more so than found for methane in earlier calculations. The surfaces are averaged over a very accurate, recent ab initio force field to give values for the couplings in silane and its variously deuterated isotopomers over a range of temperatures. For J(Si, H) in (SiH4)-Si-29 both stretching and bending contribute to the nuclear motion effects with the former being considerably larger numerically. For J(H,D) in (SiH3D)-Si-28 the bending and stretching contributions are both substantial but, being of opposing sign, cancel each other out, leaving the bending-stretching cross terms to give most of the remaining contributions. The calculated values are in excellent agreement with new experimental values presented in this work; for (1)J(Si, H) in (SiH4)-Si-29 and (SiHD3)-Si-29 at 298 K we calculate -199.9 Hz and -198.5 Hz, respectively, to be compared with experimental values of -201.3 (+/-0.4) Hz and -199.9 (+/-0.4), Hz respectively. For (gamma (H)/gamma (D)) J(H,D) we predict a value of 2.58 Hz, to be compared with 2.61 (+/-0.08) Hz obtained by experiment at 298 K. Calculation of the tensor components of all parts of the one-bond and two-bond couplings are reported for equilibrium geometry and compared to newly calculated values of the corresponding components of methane. The principal finding for the one-bond coupling is that K-parallel to>K-perpendicular to for silane and K-parallel to