Ground-state calculations

The predicted eneigy is given in the final CAS iteration (this is from the ground state calculation) ... 

Our best estimation for the vertical excitation energies for states of A, symmetry are reported in Table 12. They correspond to a ground state calculated at CI( 6) level using orbitals optimized for the neutral molecule with the MCSCF/SD expansion, and excited Rydberg states calculated at the level using orbitals optimized for the positive ion... 

By the way, through ensemble theory with unequal weights, Ref. [68] identifies an effective potential derivative discontinuity that links physical excitation energies to excited Kohn-Sham orbital energies from a ground-state calculation.)... 

One has to be very cautious in interpreting, e.g., valence band spectra of actinides generally a direct comparison of valence band spectra with the density of states as derived from band ground state calculations is not appropriate. 

If the system of interest has a spin-degenerate ground state, calculate the g-tensor and/or ZFS if required, determine the energy of the components of the ground state in the presence of the applied magnetic field, and evaluate the necessary temperature-dependent factors. 

We now consider the theoretical calculation of excited-state wave functions. This is more difficult than ground-state calculations because we are dealing with open-shell configurations. The Hartree-Fock equations for a state of an open-shell configuration have a more complicated form than for closed shells, and there exist close to a dozen different approaches to excited-state Hartree-Fock calculations. As noted earlier, the Hartree-Fock wave function for a closed-shell state is a single determinant, but for open-shell states, we may have to take a linear combination of a few Slater determinants to get a Hartree-Fock function that is an eigenfunction of S and Sz and has the correct spatial symmetry. 

Since the ground state of tetrahedral complexes is orbitally degenerate (37i), it can be expected that the shifts observed in NMR spectra of pseudotetrahedral complexes are due to both contact and pseudocontact contributions. Kurland and McGarvey436 have derived the equations for calculating contact and pseudocontact terms in complexes with nearly orbitally degenerate ground states. Calculations of NMR shifts in pseudotetrahedral complexes are reported in ref. 437. Selected examples of pseudotetrahedral complexes whose NMR spectra have been studied are reported in Table 28 and ref. 455. 

The harmonic frequencies for the ground state calculated with the MCHF wavefunctions, as well as the dissociation energy 3 +... 

We have now achieved a situation in which dielectric continuum solvation models in general, and especially COSMO, are quite well established for SCF ground-state calculations of organic molecules. Many of the methods, tools, and properties available for gas-phase calculation can also be performed in a dielectric continuum solvation model. The PCM model including C-PCM provides the greatest breadth of implemented functionality. 

Deconvolution of spectra (energy distribution of orbitals and widths of bands) accomplished by comparison of variable energy photoelectron spectra and SCF-Jfct -SW ground state calculation. 

When considering reaction paths on PE surfaces of excited electronic states, as required for the rationalization of photochemistry, reliable ab initio energy calculations are much more difficult than ground-state calculations. First, because excited-state electronic wave-functions are typically of multiconfigurational character, and secondly, because multidimensional surface crossings are the rule rather than the exception for excited states. 

He has been the subject of three papers, the first being concerned with a one-centre calculation of the direct ionization of He by He+ impact, which is considered to arise from a molecular autoionization of the 2E state of He as it crosses the boundary of the continuum (He j+ + e ).87 A second paper describes a ground-state calculation with a Slater basis,88 and the third a FSGO study.37... 

The HF calculations predict a 3II ground state, which is the same as found for CaO, but as noted above, Cl might well reverse this ordering, and it is clear that very extensive calculations are needed before this question is definitely settled. A very recent paper reporting PE curves for BeO, MgO, and CaO, using DZ + P basis sets, has also appeared,310 and the authors also discuss the dissociation behaviour of the ground state. Calculation of the spin-orbit matrix elements shows that 3I1 and 12+ states are not significantly mixed. 

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