Dispersion of one-body operators with the Balian-Veneroni variational principle

Using the variational principle proposed by Balian and Veneroni we calculate the dispersion of several one-body observables. Within the Lipkin-Meshkov-Glick model, a comparison with exact results shows that a good agreement on the dispersion is obtained whenever the time-dependent Hartree-Fock (TDHF) method predicts accurately the expectation value of the observable. An application to the more realistic case of a three-dimensional collison of two 16O nuclei shows a significant increase of the dispersion in the number of transferred nucleons over a simple TDHF prediction. (orig.)