### Browsing by Author "Schlegel, H. Bernhard"

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Item Proton Transfer Studied Using a Combined Ab Initio Reactive Potential Energy Surface with Quantum Path Integral Methodology(Journal of Chemical Theory and Computation, 2010-08) Wong, Kim F.; Sonnenberg, Jason L.; Paesani, Francesco; Yamamoto, Takeshi; Vaníček, Jiří; Zhang, Wei; Schlegel, H. Bernhard; Case, David A.; Cheatham, Thomas E. III; Miller, William H.; Voth, Gregory A.; Beverly K. Fine School of the SciencesThe rates of intramolecular proton transfer are calculated on a full-dimensional reactive electronic potential energy surface that incorporates high-level ab initio calculations along the reaction path and by using classical transition state theory, path-integral quantum transition state theory, and the quantum instanton approach. The specific example problem studied is malonaldehyde. Estimates of the kinetic isotope effect using the latter two methods are found to be in reasonable agreement with each other. Improvements and extensions of this practical, yet chemically accurate framework for the calculations of quantized, reactive dynamics are also discussed.Item Theoretical Studies of An(II)(2)(C(8)H(8))(2) (An = Th, Pa, U, and Np) Complexes: The Search for Double-Stuffed Actinide Metallocenes(Inorganic Chemistry, 2010-07-19) Zhou, Jia; Sonnenberg, Jason L.; Schlegel, H. Bernhard; Beverly K. Fine School of the Sciences; ChemistryComplexes of the form An(2)(C(8)H(8))(2) (An = Th, Pa, U, and Np) were investigated using density functional theory with scalar-relativistic effective core potentials. For uranium, a coaxial isomer with D(8h) symmetry is found to be more stable than a C(s) isomer in which the dimetal unit is perpendicular to the C(8) ring axis. Similar coaxial structures are predicted for Pa(2)(C(8)H(8))(2) and Np(2)(C(8)H(8))(2), while in Th(2)(C(8)H(8))(2), the C(8)H(8) rings tilt away from the An-An axis. Going from Th(2)(C(8)H(8))(2) to Np(2)(C(8)H(8))(2), the An-An bond length decreases from 2.81 A to 2.19 A and the An-An stretching frequency increases from 249 to 354 cm(-1). This is a result of electrons populating An-An 5f pi- and delta-type bonding orbitals and varphi nonbonding orbitals, thereby increasing in An-An bond order. U(2)(C(8)H(8))(2) is stable with respect to dissociation into U(C(8)H(8)) monomers. Disproportionation of U(2)(C(8)H(8))(2) into uranocene and the U atom is endothermic but is slightly exothermic for uranocene plus (1)/(2)U(2), suggesting that it might be possible to prepare double stuffed uranocene if suitable conditions can be found to avoid disproportionation.