  We present a new theoretical approach, unrestricted self-energy embedding
theory (USEET) that is a Green's function embedding theory used to study
problems in which an open, embedded system exchanges electrons with the
environment. USEET has a high potential to be used in studies of strongly
correlated systems with odd number of electrons and open shell systems such as
transition metal complexes important in inorganic chemistry. In this paper, we
show that USEET results agree very well with common quantum chemistry methods
while avoiding typical bottlenecks present in these method.
