Optimal charge and charge response determination through conformational space: global fitting scheme for representative charge and charge response kernel.
We propose a global fitting scheme derived in the least-squares sense to estimate the optimal partial charge and charge response kernel (CRK), partial differential(Q(a))/partial differential(V(b)), with the data collected from conformational space sampling. We applied the global fitting method to the 1-butanol system and show the performance and accuracy of our global fitting procedure. In addition, we chose 1-pentanol as the test system for electronic structure change through conformational change and applied the global fitting method to it. From our study, it is indicated that intramolecular polarization can be influenced by intramolecular hydrogen bonding, and it is shown that our global fitting method can correspond to such a situation. Also, the global fitting procedure was tested on a large molecular system, 1-dodecanol. We show the results of the application of our fitting method for the system needed to sample large sets of data over a large conformational space. It is indicated that the nonlocality in intramolecular polarization in the alkyl chain sequence can be observed and that the large fluctuation of CRKs through nonbonded interactions such as intramolecular hydrogen bonding, as seen in the 1-pentanol case, can appear in common. The global fitting scheme we propose can be used for building molecular models considering polarization effects explicitly, even in the case of target systems that include many conformers.
Ishida
Tateki
T
Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan. ishida@ims.ac.jp