
Ground state of the quantum Jahn-Teller model with broken rotational symmetry was investigated by the variational approach in two cases: a lattice and a local ones. Both cases differ by the way of accounting for the nonlinearity hidden in the reflection-symmetric Hamiltonian. In spite of that the ground state energy in both cases shows the same features: there appear two regions of model parameters governing the ground state: the region of dominating selftrapping modified by the quantum effects and the region of dominating phonon-assisted tunneling (antiselftrapping). In the local case (i) the effect of quantum fluctuations and anharmonicity due to the two-mode correlations is up to two orders larger than contributions due to the reflection effects of two-center wave function; (ii) the variational results for the ground state energy were compared with exact numerical results. The coincidence is the better the more far away from the transition region at the E$\otimes$e symmetry where the variational approach fails.
18 pages, 7 figures, published in Adv.in Quantum Chemistry
Condensed Matter - Other Condensed Matter, Condensed Matter - Materials Science, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Other Condensed Matter (cond-mat.other)
Condensed Matter - Other Condensed Matter, Condensed Matter - Materials Science, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Other Condensed Matter (cond-mat.other)
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