QUantum Electron Simulation Toolbox (QUEST) is a Fortran 90/95 package that implements the Determinant Quantum Monte Carlo (DQMC) method for quantum electron simulations. The original versions of DQMC programs, developed by the condensed matter theory group at UCSB including R. L Sugar, D. J. Scalapino, S. R. White, and E. Y. Loh, and maintained by R. Scalettar, have been extensively used to study magnetism, metal-insulator transitions, and superconductivity by the Hubbard model. QUEST, the new version of DQMC simulations, serves three purposes.
  1. To improve simulation performance: QUEST has improved the performance of simulations by using new algorithms, like prepivoting and delayed update, and by integrating modern numerical kernels, BLAS/LAPACK. Also, QUEST has GPU experimental support via CUDA and CUBLAS. A six to eight times speedup had been observed for medium sized simulations.
  2. To integrate existing programs: QUEST has integrated many legacy codes by modularizing their computational components, which makes QUEST not only a single program, but a toolbox. The advantages of modularization also include the ease of maintenance and the convenience of program interfacing.
  3. To assist new simulations development: QUEST has several desired properties for developing new simulations, such as the ability of creating new lattice geometries. Several novel simulations had been done by using QUEST.

Development of QUEST is supported through a SciDAC (Scientific Discovery through Advanced Computing) grant by the U.S. Department of Energy - Office of Science, Advanced Scientific Computing Research and the National Nuclear Security Agency under the contract number DE-FC-02-06ER25793. It is a part of the project on "Modeling Materials at the Petascale: next generation multi-scale quantum simulation software for strongly correlated materials".

The project is also supported in part by NSF grant PHY1005502 and used resources of the National Energy Research Scientific Computing Center, which is supported is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.