Speaker
Prof.
Takao Tsuneda
(University of Yamanashi)
Description
The significance of long-range exchange interactions is presented from the viewpoint of DFT in quantum chemistry [1] in the first part, and then, it is shown focusing on chemical reactions in the second part.
So far, we have developed the long-range corrected (LC) DFT [2] and have applied it to a wide variety of chemical and physical properties [3]. As a result, we have confirmed that the long-range exchange interactions are required to calculate various types of the properties: e.g. charge transfer excitations [4], van der Waals bonds [5], nonlinear optical properties [1] and so forth. Orbital energies may be the most significant property that LC-DFT makes it possible to calculate quantitatively [6]. Since orbital energies are the solution of the Kohn-Sham equation, this indicates that the long-range correction essentially improves DFT (or exactly the generalized DFT). In the first part, I will briefly review our past studies on LC-DFT.
Recently, we are investigating chemical reactions using the quantitative orbital energies. As the exact orbital energies are proven to inhere, LC-DFT orbital energies hardly vary dependent on occupation numbers. Chemical reactions usually proceed through charge transfers in the initial processes. We found that LC-DFT orbital energies are kept almost constant in the initial processes of many reactions, and then, they rapidly increase toward the products [7]. We have recently developed an orbital energy-based reaction theory as the modification of conceptual DFT [8]. I will present this topic in the second part.
1. T. Tsuneda, ``Density Functional Theory in Quantum Chemistry’’ (Springer, 2014).
2. H. Iikura, T. Tsuneda, T. Yanai, and K. Hirao, J. Chem. Phys., 115, 3540 - 3544, 2001.
3. T. Tsuneda and K. Hirao, WIREs Computational Molecular Science 4, 375 - 390, 2014.
4. T. Tsuneda and K. Hirao, ``Time-Dependent Density Functional Theory’’, in ``Theoretical and Quantum Chemistry at the 21st Century Dawn End’’ (Apple Academic Press, 2017).
5. T. Tsuneda and T. Taketsugu, ``π-Stacking on Density Functional Theory: A review’’, in ``π-Stacked Polymers and Molecules’’, Ed. T. Nakano, 245 - 270 (Springer, 2013).
6. T. Tsuneda, J.-W. Song, S. Suzuki, and K. Hirao, J. Chem. Phys. 133, 174101(1 - 9), 2010.
7. T. Tsuneda and R. K. Singh, J. Comput. Chem. 35, 1093 - 1100, 2014.
8. T. Tsuneda, ``Chemical reaction analyses based on orbitals and orbital energies’’, Int. J. Quantum Chem. Special Issue on ``Theoretical Chemistry in Japan’’ 115, 270 - 282, 2015.
