BALOO: A Fast and Versatile Code for Accurate Multireference Variational/Perturbative Calculations

We present the new BALOO package for performing multireference variational/perturbative computations for medium- to large-size systems. To this end we have introduced a number of conceptual and technical improvements including full parallelization of the code, use and manipulation of a large panel of reference orbitals, implementation of diagrammatic perturbation treatment, and computation of properties by density matrix perturbed to the first-order. A number of test cases are analyzed with special reference to electronic transitions and magnetic properties to show the versatility, effectiveness, and accuracy of BALOO.