Knowledge Bank

The barrier to internal rotation in $H2O2$ has been investigated in the Hartree-Fock approximation using a contracted [4s 3p 1d/2s 1p] set of Gaussian functions. At each dihedral angle considered [$0+$ (cis), $60\ast$, $120\ast$, $180\ast$ (trans)] all geometrical parameters have been optimized. Expanding the energy in a Fourier series, we obtain (in $cm-1$) {V}({e})=1217 \cos \phi+722 \cos 2\phi+51 \cos 3\phi\mbox{V(trans}=384\mbox{ cm}^{-1}\mbox{V(cis)}=2919\phi_{o}=114^{\circ} The experimental values of V (trans), V (cis) and $\varphi o$ obtained by Ewig and $Harris1$ from a re-analysis of the data of Hunt, Leacock, Peters, and $Hecht2$ are $386cm-1$, $2649cm-1$ and $112\circ$. Work is presently under way to further refine the potential curve. Using the finite difference method, the wave equation describing the relative motion of the two rotors in this potential is being solved to determine the wavefunctions and energies of the torsional states. In addition to providing information on the spectrum of $H2O2$ in the infrared region, the nuclear wavefunctions will be used to compute such properties as the average dihedral angle, dipole moment, etc., in the various torsional states.