Journal of Physical Chemistry A, Vol.121, No.16, 3142-3147, 2017
Orbitals, Occupation Numbers, and Band Structure of Short One-Dimensional Cadmium Telluride Polymers
Recent work found that soldering CdTe quantum dots together with a molecular CdTe polymer yielded field-effect transistors with much greater electron mobility than quantum dots alone. We present a computational study of the CdTe polymer using the active-space variational two-electron reduced density matrix (2-RDM) method. While analogous complete active-space self-consistent field (CASSCF) methods scale exponentially with the number of active orbitals, the active-space variational 2-RDM method exhibits polynomial scaling. A CASSCF calculation using the (48o,64e) active space studied in this paper requires 1024 determinants and is therefore intractable, while the variational 2-RDM method in the same active space requires only 2.1 x 10(7) variables. Natural orbitals, natural-orbital occupations, charge gaps, and Mulliken charges are reported as a function of polymer length. The polymer, we find, is strongly correlated, despite possessing a simple sp(3)-hybridized bonding scheme. Calculations reveal the formation of a nearly saturated valence band as the-polymer grows and a charge gap that decreases sharply with polymer length.