Studies of chemical reactions and molecular properties

  • Computation of Stokes Shift in Π-Conjugated Organic Systems.

    In collaboration with the Yamaguchi group at Nagoya University we are computing the electronic and molecular structure of p-conjugated electron systems in their ground and excited states, in gas phase as well as in solution.

  • Design of Novel Organic Catalysts.

    In collaboration with the group of Prof. Susumu Saito at Nagoya University we are trying to design hitherto unknown organic compounds and molecular catalysts, as well as control structure and functions of each molecule and/or their assembly.

  • Application of DFTB Analytical Second Derivatives.

    We apply DFTB analytical second derivatives and field derivatives for the calculation of IR and Raman spectra of systems up to thousands of atoms. We have successfully applied this technique in studies on the convergence behavior of 1.) diameter, 2.) chirality, and 3.) length of finite size graphenes and CNTs. In addition, the spectra of fullerene cages have been computed and compared with experimental data. This work is carried out in close collaboration with the group of Prof. Henryk A. Witek at the National Chiao Tung University, Taiwan.

  • Characterization and Quantification of Interaction Energies between Graphene Sheet Layers in Carbon Onions and Multi-Walled Carbon Nanotubes.

    Using systematic comparisons for smaller model systems such as the benzene dimer, we have established the accuracy of the computationally very economically RI-MP2 variant with respect to conventional MP2 calculations in the context of carbon nanostructures. RI-MP2 allows the treatment of chemical systems with several hundred atoms, and can therefore be used to compute, for instance, C60@C240. We have demonstrated that the dispersion-corrected version of DFTB (DFTB-D) yields reasonable agreement for this system, and are planning to extend such studies to double- and multi-walled CNTs. CNT-CNT interaction is another area that we will focus our attention on with RI-MP2 and DFTB-D. Here, experimental data is scarce and the ones available are conflicting. This research is carried out in collaboration with the group of Prof. Nakai at Waseda University, Tokyo. We also study adsorption of small molecules on graphitic surfaces in collaboration with Prof. Eric Borguet at Temple University.

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