We extend the frozen density embedding theory to non-integer subsystems' particles numbers. Different features of this formulation are discussed, with special concern for approximate embedding calculations. In particular, we highlight the relation between the non-integer particle-number partition scheme and the resulting embedding errors. Finally, we provide a discussion of the implications of the present theory for the derivative discontinuity issue and the calculation of chemical reactivity descriptors.
@article{arxiv.1403.4449,
title = {Frozen density embedding with non-integer subsystems' particle numbers},
author = {E. Fabiano and S. Laricchia and F. Della Sala},
journal= {arXiv preprint arXiv:1403.4449},
year = {2014}
}