Metastable Molecules and Other Energetic Structures: The Contribution of Theory

摘要

We have emphasized a rational theoretical design of new energetic metastablemolecules that is based on highly accurate electron correlated coupled-cluster theory and directed toward a search of 'synthesizable' species that have a high heat of formation (large specific impulse) and can be reasonably stable. We have investigated the molecular mechanisms of the initial steps in exothermic decomposition (initial steps of ignition and explosion), as well as possible synthetic roots in the synthesis of the desired metastable isomers. Based on the goal of developing theoretical methods that can provide sufficiently high accuracy (to be competitive with what experimental methods can achieve for the characterization of molecular structure and properties), we have formulated and implemented in the ACES II program the following new 'tools': (1) ROHF-CC and ROHF-MBPT methods for the treatment of open-shell systems that might be subject to spin contamination in UHF; (2) analytical gradients for ROHF-CC and ROHF-MBPT; (3) the equation of motion coupled-cluster (EOM-CC) approach for excited, electron attached, and ionized states; (4) triple excitation's for excited-state energies; (5) simplified (partitioned) EOM-CC methods for application to large molecules; and (6) EOM-CC method for computations of properties, including NMR coupling constants.