Ab initio study of three-fold methyl torsion in 2-methyl-3-hydroxypyridine in ground electronic state (S0)

The molecule 2-methyl-3-hydroxypyridine has been studied systematically using ab initio calculations in ground electronic state (S0). In this paper, we have focused to investigate the methyl torsional potential barrier and its origin in the S0 state of the molecule. Hartree-Fock (HF), second order Mollar-Plesset perturbation (MP2) and B3LYP density functional level of theories with various types of Gaussian basis sets were used to obtain the minimum energy conformation of the molecule. B3LYP/TZVP level of theory were used for further investigations along with natural bond orbital (NBO) calculations which have been performed to get insight into the barrier potential formation. The present study reveals that the local interactions to methyl group are the responsible term for the formation of the barrier potential.