2 papers
cond-mat.stat-mech2015
Correlation functions from a unified variational principle: trial Lie groups
Roger Balian, Marcel Veneroni
Time-dependent expectation values and correlation functions for many-body quantum systems are evaluated by means of a unified variational principle. It optimizes a generating funct…
nucl-th1997
Extended BCS Theories
R. Balian, H. Flocard, M. Vénéroni
Extensions of the Hartree-Fock-Bogoliubov theory are worked out which are tailored for, (i) the consistent evaluation of fluctuations and correlations and (ii) the restoration thro…