**************** The 11th., Lab Seminar ****************************

Date: Mon, October 15, 2000  PM 1:30-

Place: No.616 Seminar room
　　　　　　 Graduate School of Information Science

Speaker: Yoshiyuki Koyano

Title: Structural Optimization of Ammonia Ionization Process 
in Aqueous Solution via Free Energy Gradient Method

Abstract:
 The free energy gradient (FEG) method has been developed as a theoretical 
method to clarifythe solvation structures of solute molecules in solution. 
In the present study, by applying the FEG method combined with QM/MM-MD 
method, the stable state (SS) and transition state (TS) structures for 
ionization　process of ammonia in aqueous solution was optimized. In addition, 
the vibrational analysis on the free energy surface was executed for the 
solute structures optimized at SS and TS in solution. Using the vibrational 
frequencies at SS and TS structures, the contributions to the free energy 
of activation were computed from the vibrational partition function. Further, 
the vibrational frequency shifts induced by the presence of the surrounding 
solvents were investigated in use of the difference solute electron density 
map and the geometry and orientation of the solute and solvents.

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