(initial)—neutral—state and the SAC-CI wave function for the final—ionized—
state. This approach allows the calculation of the relative intensity of the peaks and
includes both initial- and final-state correlation effects.
In this work, we compared the calculated ionization potentials with the values
obtained from the Koopmans theorem. This theorem states that for an N-electron
Hartree-Fock (HF) single-determinant wave function the ionization potential (I.P.)
to ionize an electron from a certain orbital equals minus the HF energy of this
orbital [12]. The reported Koopman’s values correspond to these values.
In Fig. 1 we present the optimized structures of three molecules previously
studied. In Fig. 2 we display the geometries of the two converged conformers of
nitromethane obtained in this work.
The reported nitromethane spectrum is a convolution of the computed discrete
SAC-CI/Monopole Approximation results for both conformers. We employed the
same weights for both spectra because the electronic barrier between them is very
small (see below). For this purpose, we used two Gaussian distribution functions
with two different full width at half maximum (FWHM) values for different regions
of the spectrum. We did not shift the energies of the calculated spectra.
Fig. 1 Converged
geometries of previously
studied molecules
150
I. Borges Jr. and E. Uhl
state. This approach allows the calculation of the relative intensity of the peaks and
includes both initial- and final-state correlation effects.
In this work, we compared the calculated ionization potentials with the values
obtained from the Koopmans theorem. This theorem states that for an N-electron
Hartree-Fock (HF) single-determinant wave function the ionization potential (I.P.)
to ionize an electron from a certain orbital equals minus the HF energy of this
orbital [12]. The reported Koopman’s values correspond to these values.
In Fig. 1 we present the optimized structures of three molecules previously
studied. In Fig. 2 we display the geometries of the two converged conformers of
nitromethane obtained in this work.
The reported nitromethane spectrum is a convolution of the computed discrete
SAC-CI/Monopole Approximation results for both conformers. We employed the
same weights for both spectra because the electronic barrier between them is very
small (see below). For this purpose, we used two Gaussian distribution functions
with two different full width at half maximum (FWHM) values for different regions
of the spectrum. We did not shift the energies of the calculated spectra.
Fig. 1 Converged
geometries of previously
studied molecules
150
I. Borges Jr. and E. Uhl