Computaitinal Approaches to Quantum Critical Phenomena

P1 - P5

P6 - P10

P11 - 15

P16 - P20


P11	Nobuya Maeshima	Dynamical properties of photoexcited states in one-dimensional dimerized Mott insulators
P12	Shiro Sakai	Quantum Monte Carlo study of the multiorbital Hubbard model with spin and orbital rotational symmetries
P13	Canceled	Canceled
P14	Yoichi Asada	The Anderson transitions in 3D, 2D, and below 2D
P15	Sei Suzuki	Mean field quantum annealing

P12	Quantum Monte Carlo study of the multiorbital Hubbard model with spin and orbital rotational symmetries.

Shiro Sakai

Combining the Trotter decomposition and a series expansion of the partition function with respect to Hund's exchange coupling, we develop a new quantum Monte Carlo (QMC) algorithm for multiorbital systems with spin and orbital rotational symmetries. While the conventional QMC method has difficulties to treat the spin-flip and the pair-hopping terms of the Hamiltonian, we show that our new approach enables us to simulate these terms efficiently.

To demonstrate this, we apply our algorithm for studying ferromagnetism in the two-orbital Hubbard model within dynamical mean field theory (DMFT).

Our results reveal how important it is to account for the correct SU(2) symmetry of Hund's exchange. Otherwise, i.e., for an Ising (Z₂) symmetry, Curie temperatures are grossly overestimated.

We also calculate the t_2g spectral functions of Sr₂RuO₄ by three-band DMFT calculations with tight-binding parameters from the local density approximation as input and with proper rotational symmetries, which has been impossible before.