H2O AS A 3-BODY SYSTEM

The few-body method for treating water molecules is presented. H2O can be regarded as a three-body system. The total three-body wavefunction is expanded in terms of the harmonic oscillator product states in the Jacobi coordinates. The binding energies are calculated by using a pa irwise model potential in the variational approach. The geometry and m odes, of internal motion are analyzed by the shape density function. T he results are E = -76.07 a. u, R(Ho) = 0.970 Angstrom and angle HOH = 105.38 degrees. These results are compared with some known calculatio ns and experimental values.