Distributional exact diagonalization formalism for quantum impurity models

Exact diagonalization of quantum lattice models on coprocessors

We implement the Lanczos algorithm on an Intel Xeon Phi coprocessor and compare its performance to a multi-core Intel Xeon CPU and an NVIDIA graphics processor. The Xeon and the Xeon Phi are parallelized with OpenMP and the graphics processor is programmed with CUDA. The performance is evaluated by measuring the execution time of a single step in the Lanczos algorithm. We study two quantum latt...

Exact diagonalization and Quantum Monte Carlo studies of quantum dots

We report exact diagonalization and diffusion quantum Monte Carlo calculations of quantum dots (QDs) in which energetics due to electron-electron interactions, magnetic field, and geometrical factors compete and induce interesting ground state configurations. The geometrical effects are generated by different confining potentials such as parabolic shaped, ring shaped, and disordered potentials....

Multilevel algorithm for quantum-impurity models.

A continuous-time path integral quantum Monte Carlo method using the directed-loop algorithm is developed to simulate the Anderson single-impurity model in the occupation number basis. Although the method suffers from a sign problem at low temperatures, the new algorithm has many advantages over conventional algorithms. For example, the model can be easily simulated in the Kondo limit without t...

Classical and Quantum Monte Carlo Algorithms and Exact Diagonalization

Exact time-dependent density functional theory for impurity models.

We employ the density matrix renormalization group to construct the exact time-dependent exchange-correlation potential for an impurity model with an applied transport voltage. Even for short-ranged interaction we find an infinitely long-ranged exchange-correlation potential which is built up instantly after switching on the voltage. Our result demonstrates the fundamental difficulties of trans...