Electronic Structure of Molecules

The chemistry of small polyatomic molecules can often be studied using ab initio theoretical computations even when experimental approaches fail. Sometimes theory can be help to interpret experimental results. The most common computational approach is via Hartree-Fock (self-consistent-field) methods. For example, the spectrum of such an apparently simple molecule as carbon disulfide (CS2) is extremely complicated and difficult to assign to specific molecular states. We have performed configuration interaction calculations on the ground and lowest lying excited states of CS2 [Tseng and Poshusta, ref_1]. The results reveal a previously uncharacterized bent (or cyclic) conformer of CS2 in the ground state potential energy hypersurface.