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This does not exclude the possibility, that larger structural fragments (such as tetra-mers and pentamers) can also contribute to the low-frequency vibrational spectrum around the boson peak. On the basis of these results, the following model of the glass transition of glycerol can be proposed. At temperatures far above Tg (186 K), the lifetime of the MRO(More)
Recently synthesized by the group of Sadler, the platinum(IV) diazido complexes [Pt(N(3))(2)(OH)(2)(L')(L'')] (L' and L'' are N-donor ligands) have potential to be used as photoactivatable metallodrugs in cancer chemotherapy. In the present study optimized structures and UV-Vis electronic spectra of trans,trans,trans- and(More)
Converged first-principles proton affinities (PA) of ammonia and carbon monoxide have been determined by the focal-point analysis (FPA) approach, thus fixing the high and low ends of the molecular proton affinity scale. The electronic structure computations employed the all-electron (AE) coupled-cluster (CC) method up to single, double, triple, quadruple,(More)
Advances in theory and algorithms for electronic structure calculations must be incorporated into program packages to enable them to become routinely used by the broader chemical community. This work reviews advances made over the past five years or so that constitute the major improvements contained in a new release of the Q-Chem quantum chemistry package,(More)
A hybrid quantum mechanical/molecular mechanical (QM/MM) potential energy function with Hartree-Fock, density functional theory (DFT), and post-HF (RIMP2, MP2, CCSD) capability has been implemented in the CHARMM and Q-Chem software packages. In addition, we have modified CHARMM and Q-Chem to take advantage of the newly introduced replica path and the nudged(More)
DNA damage by attachment of low-energy secondary electrons is a very interesting and important mechanism. Electron capture and subsequent base release are thought to be the elementary steps of this mechanism. The process of the N1-glycosidic bond breaking of anion radicals of pyrimidine nucleosides, specifically the 2'-deoxyribothymidine (dT) and(More)
The singlet electronic ground state isomers, X (1)Sigma(g) (+) (AlOAl D(infinityh)) and X (1)Sigma(+) (AlAlO C(infinitynu)), of dialuminum monoxide have been systematically investigated using ab initio electronic structure theory. The equilibrium structures and physical properties for the two molecules have been predicted employing self-consistent field(More)
Structures, accurate relative energies, equilibrium and vibrationally averaged rotational constants, quartic and sextic centrifugal distortion constants, dipole moments, (14)N nuclear quadrupole coupling constants, anharmonic vibrational frequencies, and double-harmonic infrared intensities have been determined from ab initio electronic structure(More)
Dative, or nonoxidative, ligand coordination is common in transition metal complexes; however, this bonding motif is rare in compounds of main group elements in the formal oxidation state of zero. Here, we report that the potassium graphite reduction of the neutral hypervalent silicon-carbene complex L:SiCl4 {where L: is:C[N(2,6-Pri2-C6H3)CH]2 and Pri is(More)