VALENCE BOND STUDY OF HYDROGEN BOND .I.

A valence bond calculation for the four electrons involved in the straight hydrogen bond O-H … O without excess charges is performed nonempirically. Five valence bond structures proposed by Tsubomura are adopted, z. e., (I) O-H O, (II) O-H+ O, (III) O++H- O, (IV)O-H—O+ and (V) OH- O+. The calculations are done for both trigonal and tetrahedral hybrid atomic orbitals of oxygen atoms. The adiabatic potential of the proton is calculated as a function of the 0…0 and the O-H distances. The shifts of the equilibrium O-H distance and of the O-H frequency with the formation of the hydrogen bond are studied. When different orbital exponents are used in the atomic orbitals of O, O- and O+, and H and H-, according to Slater's rule, the obtained shifts agree qualitatively with experiment, although the absolute values deviate from experimental ones in the short hydrogen bond. © 1969, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.