Fast and near-exact FCI.
Dice is a program principally written by Sandeep Sharma that implements the semistochastic heat bath configuration interaction (SHCI) algorithm for ab initio Hamiltonians of quantum chemical systems.
Unlike full configuration interaction (FCI), SHCI can be used to treat active spaces containing 30 to 100 orbitals. SHCI is able to accomplish this by taking advantage of the fact that although the full Hilbert space may be enormous, only a small fraction of the determinants in the space have appreciable coefficients.
I have been a core developer of Dice since joining the Sharma Group in 2016. Over that time, I have helped improve the parallelism and memory efficiency. I’ve implemented the SHCISCF module in PySCF which uses Dice as an approximate FCI solver. In addition to techinical implementations, I created the testing suite, in-code and web-based documentation.