Fourier type potential energy function for conformational change of selected organic functional groups

- Energies of internal rotation of functional groups are calculated theoretically.
- The energies are analyzed by Fourier-series expansions.
- Rotation around bonds without lone pairs are described with one term Fourier-series.
- Two/three terms are needed in the series if the atoms in the bond have lone pairs.
- The Fourier series can reproduce the potential energy curves within 1 kJ/mol.