Pseudoenergy term

Functions such as 1 and 2 permit the inclusion of a pseudoenergy term for all pairs of protons in a molecule, whether or not cross relaxation rates are sufficiently large to be observed. This is made possible by the fact that for sufficiently long distances, the energy contributions from these functions are negligible. For cases where no connectivity is observed between a pair of protons roa6 is set equal to some distance, in our case 4.0A, beyond which a connectivity between protons would be lost in the noise. Inclusion of a pseudoenergy term in the absence of an observed connectivity is important since it serves to exclude conformers with interproton distances short enou to produce a connectivity when none is observed. We shall make limited use of this fact in our structural determinations. 

In expression 3, (Tab is the average cross relaxation rate between protons a and b Xl is the mole fraction of one of the conformers, and aiab and a2ab are the cross relaxation rates for the individual conformers. In expression 4, Ei and E2 are the molecular mechanics energies for the conformers, k is the Boltzmann constant and T is the temperature at which the data were obtained. The pseudoenergy term may be... 

Perturbation theory approaches are essentially improvements to the TDHF results. This type of work was pioneered by Rice and Handy,who defined the polarizability in terms of derivatives of a pseudoenergy, W = ( (H - ih d/dt)) ), with respect to one static and one frequency-dependent field... 

---