Incorrect diatomic dissociation in variational reduced density matrix theory arises from the flawed description of fractionally charged atoms.
The behaviour of diatomic molecules is examined using the variational second-order density matrix method under the P, Q and G conditions. It is found that the method describes the dissociation limit incorrectly, with fractional charges on the well-separated atoms. This can be traced back to the behaviour of the energy versus the number of electrons for the isolated atoms. It is shown that the energies for fractional charges are much too low.
Van Aggelen
Helen
H
Ghent University, Department of Inorganic and Physical Chemistry, Krijgslaan 281 (S3), 9000 Gent, Belgium.
Bultinck
Patrick
P
Verstichel
Brecht
B
Van Neck
Dimitri
D
Ayers
Paul W
PW