A Calculation of the Vibration Frequencies and Other Constants of the H2O Molecule

Abstract

The calculation is based on the Slater‐Pauling theory of directed valence, but supplemented by data from the band spectrum of the diatomic OH molecule. The heat of dissociation and valence angle, obtained incidentally, are in good agreement with experiment. The ``cross‐terms'' in the vibrational potential prove to be of subordinate importance. It is found that two of the fundamentals should fall near 2.8μ, and that they should almost coincide. This designation of the observed wide absorption band at 2.6–2.8μ as the superposition of two fundamentals agrees with Mecke's interpretation of the H₂O spectrum, but contradicts Johnston and Walker's. The computed value 1660 cm^—1 of the third fundamental frequency ω₃ differs from experimental determinations by only 4 percent, but any closer agreement than 15 percent is accidental in view of the approximate nature of the theory. Since ω₃ represents a primarily angular vibration, its calculation is a particular test of the concepts of directed valence.