Study of the electronic structure of molecules XXII. Additional ab initio computations for the barrier to internal rotation in polynucleotide chains

In a previous paper of this series (paper XIX) we reported an ab initia computation for the barrier to the internal rotation in the sugar-phosphate- sugar complex, C10H19O8P; the barrier corresponds to the configuration with o>"=45°, u)' = i|/' = i|i" =