Figure 7.
Considered gas-phase structures of alanine dipeptide. The relative conformational energies were obtained with dispersion-corrected PM6 and DFTB3, as well as with RI-MP2 for reference. Prior to that, the geometries were optimized on the DFT level BLYP/def2-TZVP/D3. (*) The structure α is not a stationary point on the BLYP/D3 PES; therefore, the geometry was obtained with restrained minimization to keep the dihedrals φ and ψ fixed.