Ushnish Ray

C Stochastics Series Expansion Runner (CSSER)

​This is C/C++ based API that can be used to model lattice based Hamiltonians. The algorithm follows Anders Sandvik's Stochastic Series Expansion (SSE) algorithm together with additional tweaks. The code is quite efficient enabling simulation of some of the largest system sizes possible involving > 200,000 particles at ultra low entropies. The code can be easily modified to handle a wide range of Hamiltonians.

Access: github (

Cloning Algorithm for Non-equilibrium Stationary States (CANSS)
​This code allows simulation of non-equilibrium stationary states based on the cloning algorithm together with tweaks that enable large scale parallel computations. It connects with LAMMPS to allow MD-based simulations. We are able to capture rare fluctuations of large realistic systems involving more than 10000 atoms.
Access: github (


Python based quantum chemistry toolkit maintained by Dr. Chan's group at Caltech. It offers a powerful library to compute a range of ab initio methods such as Hartree-Fock, CASSCF, Coupled Cluster, DMRG-SCF and FCI. 

​​Access: github (

Below are links to code bases used in my research.