Raman scattering in crystalline oligothiophenes: A comparison between density functional theory and bond polarizability model

被引:35
作者
Hermet, P.
Izard, N.
Rahmani, A.
Ghosez, Ph.
机构
[1] Univ Liege, Dept Phys, B-4000 Sart Tilman Par Liege, Belgium
[2] Univ Montpellier 2, CNRS, UMR 5587, Lab Colloides Verres & Nanomat, Montpellier 5, France
[3] Univ MY Ismail, Dept Phys, Meknes 50000, Morocco
关键词
D O I
10.1021/jp064700n
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Raman intensity of intramolecular and lattice modes of crystalline alpha-bithiophene (alpha-2T) are investigated within density functional theory using a nonlinear response formalism. First, comparison between the calculated Raman spectrum and the experimental data allows the assignment of the main Raman lines over the whole frequency range. Then, a bond polarizability (BP) model, limited to first neighbors, is built. We show that, although the BP model cannot reproduce the changes of dielectric susceptibility under individual atomic displacements, it is accurate enough to reproduce the profile of the unpolarized nonresonant Raman spectrum of alpha-2T powder. Finally, the BP model, fitted on our first-principles results on alpha-2T, is applied with success to the alpha-quaterthiophene polymorph phases and alpha-sexithiophene, demonstrating on practical examples that first-principles and BP approaches are powerful complementary tools to calculate the nonresonant Raman spectrum of alpha-2T and make reasonable predictions on larger oligothiophenes.
引用
收藏
页码:24869 / 24875
页数:7
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