乙醇在Pt(111)表面上的解離反應與推拉電子基分子系統的分子動態模擬之電子轉移理論研究

Abstract

Abstract: In part 1 , total energy calculation based on Density Function Theory (DFT) with Ultrasoft-pseudopotenital and generalized gradient spin-polarized approximation (GGSA) was used to investigate (1) O-H cleavage of ethanol and (2)C-H hydrogen elimination via four-membered ring and five-membered ring on Pt(111)-3x3 surface. By means of Partial Structure Constrain Path Minimization(PSCPM) method , our calculated energy barrier for O-H cleavage is 0.849eV and C-H hydrogen elimination via four-membered ring and five-membered ring are 0.319eV and 0.966eV , respectively. These results are in good agreement with TPD experimental result. Furthermore , we found that (1) less change in Pt-Pt dimmer bond length and (2) more H-Pt bond formation , less change in carbon hybrid orbital and π bonding in C=O by means of the partial density of state (PDOS) for the four-membered-ring hydrogen elimination to explain reaction selectivity. In part 2 , we performed first principle molecular dynamics based on Density Function Theory with norm-conversing pseudopotential and accurate LCAO basis set in SIESTA package on CN-CH=CH-NH2 , NO2-CH=CH-NH2 and BH2-CH=CH-NH2n push-pull molecule system and we collected dipole moment ,structure and charge trajectory in 3ps molecular dynamics. We used Fourier Transformed dipole moment AutoCorrelation Function to simulate IR spectra and analyzed characteristic vibration mode in molecule by using PaDAF and SCAF method. By comparison of Fourier Transformed charge AutoCorrelation Function (FT[charge-ACF]) and IR spectra , we found that main-chain vibration mode induced charge transfer. Furthermore , we calculated charge transfer rate by utilizing charge dynamics and explain charge transfer effect of these push-pull molecules.Finally , we also investigated temperature effect on charge transfer and calculated activation barrier of charge transfer.