L-苯丙氨酸构象和电离能的理论研究  

Theoretical study of phenylalanine:conformers and ionization energies

作　　者：王美婷[1] 关君[2] 王克栋[1] 孟举[1] 黄笑天[1] 

机构地区：[1]河南师范大学物理与电子工程学院,新乡453007 [2]新乡广播电视大学继续教育学院,新乡453003

出　　处：《原子与分子物理学报》2014年第4期525-531,共7页Journal of Atomic and Molecular Physics

基　　金：河南省教育厅研究项目(12A14006;2011A140015);河南师范大学国家级科研项目培育基金(2012PL02)

摘　　要：我们对L-苯丙氨酸进行了全势能面搜索,采用B3LYP方法优化了L-苯丙氨酸的648种可能构象,最终得到了37种稳定存在的构象.分别采用B3LYP、B3PW91、M06-2X、MP2和CCSD(T)计算了L-苯丙氨酸最稳定的10种构象的相对能量,其中M06-2X和MP2方法能够给出较好的结果.对比不同的基组,说明采用aug-cc-pVDZ已经接近达到基组收敛极限.用电子传播子理论P3近似方法计算稳定构象外价壳层轨道的垂直电离能与光电子能谱实验符合的很好;根据构象的相对能量以及理论模拟与实验的光电能谱的比对,说明对气相光电子能谱至少四种构象有贡献.The full potential energy surface of L-phenylalanine has been searched.A total of 648 unique trial structures were generated by allowing for all combinations of internal single-bond rotamers and were optimized at the DFT/B3LYP level of theory.A total of 37 local minima conformers were found. The relative energies of ten low-lying conformations are carried out with five different methods：B3LYP, B3PW91,M06-2X,MP2 and CCSD（T）.Comparing the relative energies of different methods,we find M06-2X and MP2 can predict a good result.Comparing the relative energies of different basis sets,one can draw a conclusion that the aug-cc-pVDZ basis set is high enough to give a convergent result.The vertical ionization energies of the conformers calculated with electron propagator theory P3/aug-cc-pVDZ are in good agreement with the experimental data from photoelectron spectroscopy.The relative energies of the conformations and the comparison between the simulated and experimental photoelectron spectra show that there are at least four conformations of phenylalanine in the gas-phase experiment.

关 键 词：构象 氢键 电离能 光电子能谱 

分 类 号：O641[理学—物理化学]