The binding within the ethene-argon and formaldehyde-methane complexes in the ground and electronically excited states is studied with equation of motion coupled cluster theory (EOM-CCSD), second-order Møller-Plesset perturbation theory (MP2) and density functional theory with dispersion corrections (DFT-D). Electronically excited states are studied within MP2 and Kohn-Sham DFT formalisms by ex...

The infrared spectra of the formic acid-water complexes isolated in argon matrices are reported. Both supersonic jet expansion and a conventional effusive source followed by trapping in solid argon at 10K are used to obtain the matrices. The experimental IR spectra are compared to the data obtained from high level ab initio (MP2) and DFT (B3LYP) calculations with 6-311++G(d,p) and aug-cc-pVTZ b...

The infrared spectra of 1-methylthymine (1-MeT) in argon and nitrogen cryogenic matrices are presented, for the first time. The molecular structure, conformations, vibrational frequencies, infrared intensities and Raman scattering activities of 1-MeT have been calculated by the DFT(B3LYP), MP2 and HF methods using the D95V** basis set. The theoretically predicted intensity pattern of the IR and...

This work discusses the dependence of transition state geometries on the choice of quantum chemical optimization method for the extensively studied Diels-Alder reaction. Rather significant differences are observed between post-Hartree-Fock methods and (hybrid) density functional theory, where the latter predicts larger asynchronicities. The results show that the low MP2 asynchronicity observed ...

Two electron correlation theories, second-order Møller-Plesset perturbation (MP2), and density functional (DFT) methods have been adopted to obtain fully optimized structures of styrene, trans-stilbene, and cisstilbene. Full geometry optimizations with MP2 shows that the nonplanar conformations of styrene and trans-stilbene are preferred by 0.24 (styrene) and 0.80 kcal/mol (trans-stilbene), res...

Using the long-range corrected (LC) density functional theory (DFT) scheme introduced by Iikura et al. [J. Chem. Phys. 115, 3540 (2001)] and the Coulomb-attenuating model (CAM-B3LYP) of Yanai et al. [Chem. Phys. Lett. 393, 51 (2004)], we have calculated the longitudinal dipole moments and static electronic first hyperpolarizabilities of increasingly long polymehtineimine oligomers. For comparis...

The molecular structure of 1-thia-closo-decaborane(9), 1-SB(9)H(9), has been determined by the concerted use of gas electron diffraction and quantum-chemical calculations. Assuming C(4v) symmetry, the cage structure was distorted from a symmetrically bicapped square antiprism (D(4d) symmetry) mainly through substantial expansion of the tetragonal belt of boron atoms adjacent to sulfur. The S-B ...

There has been much interest in cost-free improvements to second-order Møller-Plesset perturbation theory (MP2) via scaling the same- and opposite-spin components of the correlation energy (spin-component scaled MP2). By scaling the same- and opposite-spin components of the double excitation correlation energy from the coupled-cluster of single and double excitations (CCSD) method, similar impr...

Somatic hypermutation (SHM) of immunoglobulin (Ig) genes is initiated by the activation-induced cytidine deaminase (AID). However, the influence of chromatin on SHM remains enigmatic. Our previous cell-free studies indicated that AID cannot access nucleosomal DNA in the absence of transcription. We have now investigated the influence of nucleosome stability on mutability in vivo. We introduced ...

The nonstatistical dissociation of acetone radical cation has been studied by ab initio direct classical trajectory calculations at the MP2/6-31G(d) level of theory. A bond additivity correction has been used to improve the MP2 potential energy surface (BAC-MP2). The energy dependence of the branching ratio, dissociation kinetics, and translational energy distribution for the two types of methy...