Energy, configuration zero point

Let us consider more closely the situation in He and He . In Fig. 18.4.1 we have plotted the lattice energy, the zero point energy for the two models (18.4.1) and (18.4.5) (with y = 4.3) as well as the total energy (18.4.6) for the smoothed potential. We have also plotted the experimental (configurational) energy... 

That is, the sum of the electronic energy and nuclear repulsion energy of the molecule at the specified nuclear configuration. This quantity is commonly referred to as the total energy. However, more complete and accurate energy predictions require a thermal or zero-point energy correction (see Chapter 4, p. 68). 

Curtiss, L. A. Raghavachari, K. Pople, J. A. Gaussian-2 theory use of higher level correlation methods, quadratic configuration interaction geometries, and second-order Mpller Plesset zero-point energies. J. Chem. Phys. 1995, 103, 4192-4120. 

Fig. 2 The experimentally determined potential energy V(), expressed as a wavenumber for convenience, as a function of the angle in the hydrogen-bonded complex H20- HF. The definition of

A final complication with the version of transition-state theory we have used is that it is based on a classical description of the system s energy. But as we discussed in Section 5.4, the minimum energy of a configuration of atoms should more correctly be defined using the classical minimum energy plus a zero-point energy correction. It is not too difficult to incorporate this idea into transition-state theory. The net result is that Eq. (6.15) should be modified... 

The aim of the present study is to investigate the validity of the pairwise additivity of two-body and three-body potentials for He2Br2. These results are compared with ah initio calculations" and a simple model of the three-body potential is proposed to determine well depths and equilibrium structures for different isomeric configurations of the complex, as well as the minimum energy pathways through them. Additionally, variational methods are used to calculate the vibrational states of He2Br2. The wavefunctions of the lower states are analyzed in terms of probability distributions of the internal coordinates and the zero-point energy of the vdW cluster is evaluated. 

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