Heitler-London wave functions

Heitler-London wave function, 15-16 Helium atom, wave function for, 3 Heterolytic bond cleavage, 46, 51, 47,53 Histidine, structure of, 110 Huckel approximation, 8,9,10,13 Hydrocarbons, force field parameters for, 112... 

Moreover, the Heitler-London wave function does not correspond to the virial theorem (it does not make the average value of the potential energy equal to minus twice the average value of the kinetic energy), and it is accordingly a poor approximation to the correct wave function for the molecule. 

Contribution /x of ionic terms calculated with best screening constant of — curve 1 a molecular orbital wave function curve 2 a Heitler-London wave function curve 3 atomic orbitals. 

Fig. 5. Contribution of ionic terms to the binding energy as a function of internuclear distance, (a) Contribution /i of ionic terms for H2 molecule (see equation 25) calculated with best screening constant of a Heitler-London wave function (after Coulson and Fischer (134)). (b) Variation of the binding energy...

The electron densities for the X, states of H2 and He2 resulting from these Heitler-London wave functions are then ... 

The Heitler London wave function of H2 used to show that the electron density between the nuclei increases by an amount... 

As long as A-Y and X-Y are polar-covalent bonds, we can focus on the covalent parts of the wave function, denoted also as the Heitler-London wave function, called so after the names of the originators of this wave function [51]. Designating the active orbitals of the fragments X, A, and Y, respectively, as x, a and y, the wave functions of R is given in Eq. (7a), without the normalization constant. This equation describes X and the A-Y bond. The wave function for R is given in Eq. (7b) ... 

The first two terms correspond to the Heitler-London wave function the other two are for ionic states. The function (1.52) is, in fact, the same as (1.48) with = C2,... 

Wave function (1) is the standard covalent-ionic resonance of vb theory. The parameter k can take values from k = 0, which corresponds to the pure covalent description of the hydrogen molecule ground state (this is the wave function first considered by Wang [47] when he introduced a variable screening constant into the Heitler-London wave function), through to k — oo, which corresponds to a pure ionic description. The best wave function of the form (1), determined by invoking the variation theorem to determine the optimal screening constant, was first reported by Weinbaum [48] in 1933. 

The Heitler-London wave functions for the three states of the lowest 2 term are... 

This result is proportional to the Heitler-London wave function from p. 611, where its important role in chemistry was highlighted ... 

It is. therefore, clear that the Heitler-London wave function differs considerably and that this huge difference does not vanish when R oo. 

Thus, the Heitler-London wave function differs from this difference is huge and does not vanish, when i 00. 

Validity of Heitler-London Wave-Functions and the submolecule model. 

---