The CIsandbox is a collection of subroutines to operate on CI spaces.  In
second_quantization.f90, methods for creation/annihilation operators are
implemented that use bitwise operators on integers, i.e. the determinants
represented as bit-strings. In wavefunction.f, a derived type is used to
represent Full-CI wavefunctions. In density.f, examples of computing the 1-el
and 2-el density matrices are provided. The rest of the files deal with Fock
matrices, orbitals and integrals.

The code was mainly written to explore the CASPT2 UDL decomposition method for
direct CASPT2, but the basic subroutines are general enough to use as a sandbox
for other CI-like codes. An example Full-CI code is included as well. The
required integrals for those calculations were obtained from Molcas.

Most routines have their own documentation, so it should be fairly
straithforward to figure out how to use them.

Steven Vancoillie, December 2013, Lund
