Electronic wave function of methane C---H bond orbital

Using the delocalized bond orbital method, obtained as a linear combination of the sp³ hybrid orbitals on the carbon and 1s orbitals on the hydrogens, we have calculated the energy of methane at the distances 0·9, 1·1 and 1·3 Å as a function of the orbital exponents. A discussion is given of the results in relation to the method of using a monocentric wave function on the carbon.

The energy at 1·1 Å is −40·122 a.u. and is in a rather good agreement with the results obtained by Mills and recently by Saturno and Parr.

The error with respect to the experimental value (0·4 a.u.) is of the order of the correlation energy.