Potential energy distribution triplet state

TABLE 9. Fundamental vibrational frequencies (cm-1) and associated potential energy distributions of aniline in its lowest-lying triplet state. Calculated values were obtained from scaled B3LYP/6-311+- -G(3df,2p) harmonic frequencies... 

It is possible to construet from H an equation of motion that governs the time-evolution of the system, as well as to state the equilibrium distribution funetion for positions and momenta. Thus H (or better V) is the basie input to a eomputer simulation program. Almost universally, in computer simulation the potential energy is broken up into terms involving pairs, triplets, etc. of molecules, i.e. ... 

There is a possibility for more than one solution of the Hartree-Fock equations if different electronic states come close on a potential energy surface. Within the spin-restricted Hartree-Fock (RHF) method, singlet and triplet instabilities are distinguished, The former involves the existence of another solution with lower energy and an electron distribution of lower symmetry, normally indicating that the initially assumed geometry is incorrect. Triplet instability involves rejection of the condition of double occupancy of molecular orbitals and a spin-unrestricted Hartree-Fock (UHF) method treatment is mandatory. The triplet instability is a necessary, but insufficient, condition for a biradical character of a ground state. 

Expressions for the medium modifications of the cluster distribution functions can be derived in a quantum statistical approach to the few-body states, starting from a Hamiltonian describing the nucleon-nucleon interaction by the potential V"(12, l/2/) (1 denoting momentum, spin and isospin). We first discuss the two-particle correlations which have been considered extensively in the literature [5,7], Results for different quantities such as the spectral function, the deuteron binding energy and wave function as well as the two-nucleon scattering phase shifts in the isospin singlet and triplet channel have been evaluated for different temperatures and densities. The composition as well as the phase instability was calculated. 

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