************ The 3rd Lab Seminar ***************************************

Title : Theoretical analysis of [2+2] photocycloaddition reaction 
        mechanism

Speaker : Ito Syoko

Date : Wed. Jun. 18th, 4:00 pm

Place : Seminar room of 3F, Graduate School of Information Science

Abstract :
Photochemical reaction is one of the hottest research field. Since 
photoexcitation reactions need complicated calculations, they are 
still remain largely unexplored. Especially conical intersections (CI) 
are important to understand chemical reactions through excited states. 
In this study, I tried to establish the technique to efficiently 
predict product selectivity after passing the CI on the ground state 
potential energy surface (PES) with a simple model. And with that 
technique, I tried to analyze the product selectivity of 
experimentally-observed system.The structure calculation level is 
CASSCF(10,9)/6-31G*, and I analyzed electron states  with CiLC 
analysis.I employed cycloaddition of ethylene + ethylene as a simple 
model. To compare with the CiLC analysis results, I carried out 
dynamic reaction coordinate (DRC) calculations starting from multiple 
structures near the CI structure. Results of CiLC analysis of this 
system correspond to DRC calculations. Thus I found out that, without 
large computation of DRC calculations, product selectivity can be 
predicted by CiLC analysis.Next, I studied product selectivity of 
photocycloaddition reaction, 2-pyridone + methyl acrylate. Results of 
CiLC analysis indicates that product selectivity cannot be explained by 
the ground state PES after the passage of CI. And so I focused on the
 exited state PES. According to the results, I could conclude that 
product selectivity is determined by the stability of CI before the 
passage of CI and, moreover, interactions by orbital polarizations 
affects the CI energy.

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