Two-dimensional Bose-Holstein Model for Hard-Core Bosons: A Quantum Monte Carlo Study

<strong>School of Physical Sciences</strong> Title: <strong>Two-dimensional Bose-Holstein Model for Hard-Core Bosons: A Quantum Monte Carlo Study</strong> Speaker: <strong>Satyaki Kar </strong> (Saha Iinstitute for Nuclear Physics, Kolkata) Date: <strong>May 5, 2015</strong> <strong>Abstract: </strong>We study a two-dimensional system of hard-core bosons (HCB) coupled to optical phonons in order to obtain the ground state phase diagram. The effective Hamiltonian turns out to be an extended t-V model comprised of a nearest-neighbor repulsion and hopping terms upto the third nearest neighbors. Tuning the relative strengths of the Hamiltonian parameters, by varying the HCB-phonon coupling, sees a plethora of exotic phases there. We use Quantum Monte Carlo simulation with stochastic-series-expansion technique to investigate the appearance of charge density wave and superfluidity in this system and their homogeneous or phase-separated coexistence at/near the transition regions. We find that a sizeable (negligible) contribution from next-nearest-neighbor hopping, away from half-filling, can lead to (π, π)-supersolidity with checkerboard ordering in such systems.