Session L36 - General Poster Session II.
POSTER session, Wednesday morning, March 22
Exhibit Hall, MCC
A number of years ago, Horn and Weinstein (Phys. Rev. D30, 1256(1984)) introduced a novel nonperturbative method for calculating ground-state expectation values for Hamiltonian systems. Although close in spirit to standard variational schemes this ``t-expansion" introduces a fictional parameter t to the trial state \exp(-\hatHt/2) |\Phi\rangle wherein the limit t\rightarrow \infty yields convergence to the ground-state energy E_0 for the expansion \[ \lim _t\rightarrow \infty \frac\left\langle \Phi \right| \hatH \exp \left( -\hatHt\right) \left| \Phi \right\rangle \left\langle \Phi \right| \exp \left( -\hatHt\right) \left| \Phi \right\rangle =E_0. \] Recently Samaj et al.\ (J. Phys. A30, 1471(1997)) have generalized the t-expansion technique and the related Connected Moments Expansion to a more general canonical sequence. They then apply this canonical series to the quantum Ising model. In the present work we have expounded upon the work of Samaj et al.\ and have applied this to a number of different many-particle Hamiltonian systems.