ON THE NONLINEAR MANIFOLD ENERGY VARIATION METHOD AND EXCITED-STATE CALCULATIONS

A coupled linear-nonlinear variational scheme is adopted to highlight the efficacy of the method of minimisation of manifold energy in relat ion to the conventional method. Particularly, the viability of this ro ute in computing excited state energies is assessed. An unconstrained minimisation technique for excited states, with even better performanc e, is also put forward in the same context. Demonstrative calculations on various anharmonic oscillators reveal a substantial computational gain in every case.