Configuration interaction singly excited

The excited-state dynamics of these complex molecules have also been studied by ultrafast time-resolved spectroscopy " to elucidate the mechanistic details. The potential energy (PE) function of the first excited singlet state of the ESIPT process in salicylic acid has been calculated by ab initio MO calculations using the 6-3IG basis set at the restricted Hartree—Fock and configuration interaction single excitation (CIS) levels, as well as the semi-empitical method... 

A number of methods have been proposed for calculations of the geometries of molecules in excited states. These include CIS (Configuration Interaction Singles) and variations on CIS to account for the effect of double substitutions, as well as so-called time dependent density functional models. Except for CIS (the simplest of the methods) there is very little practical experience. There is also very little solid experimental data on the geometries of excited-state molecules. 

CIS Model. Configuration Interactions Singles. A limited Configuration Interaction scheme in which only single excitations from occupied to unoccupied molecular orbitals are considered. This is perhaps the simplest method available to the description of Excited States of molecules. 

Table 2.7 contains five columns of numbers for excitation energies in Be. The first two are from Ref. [106]. The acronyms SC-SF-CIS and FCI stand for "spin-complete, spin-flip, configuration-interaction singles" and "full configuration interaction," respectively. In this case, the application of SPSA employs the differences of only the Fermi-sea energies given in the previous subsection (15a, 16c, and 19). Also, the Fermi-sea wavefunction for the... 

CISD. CISD (configuration interaction, single double) are LCAO expressions that treat configuration interactions by including one or two excited states. The designations CISDT and CISDTQ expand this to three and four excitations, respectively. 

To study electronically excited states of molecules the most commonly and widely used single excitation based method is the configuration interaction-singles (CIS) method which is also known as the Tamm-Dancoff approximation. In the CIS approach, the excited state wave functionis... 

Configuration Interaction Singles A variational method with the trial wave function in the form of a linear combination of the given set of the singly excited Slater determinants. 

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