The potential energy surface associated with internal rotation of a pair of geminal functional groups was studied using electron structure calculations. The functional groups were attached to a methylene carbon and were chosen as saturated hydrocarbons, unsaturated hydrocarbons and heteroatom containing moieties like amide bonds in various orientations. For the majority of the studied compounds extended Fourier expansions, augmented with Gaussian functions were needed to achieve accuracy within a few kJ/mol. The present letter aims to take the first steps of a bottom up solution for protein folding by finding the functions of small peptide residues. (C) 2015 Elsevier B.V. All rights reserved.