Binder Robert, Bonfanti Matteo, Lauvergnat David, Burghardt Irene
Institute for Physical and Theoretical Chemistry, Goethe University, Max-von-Laue-Str. 7, 60438 Frankfurt/Main, Germany.
Université Paris-Saclay, CNRS, Institut de Chimie Physique, UMR 8000, 91405 Orsay, France.
J Chem Phys. 2020 May 29;152(20):204119. doi: 10.1063/5.0004510.
A generalized Frenkel-Holstein Hamiltonian is constructed to describe exciton migration in oligo(para-phenylene vinylene) chains, based on excited state electronic structure data for an oligomer comprising 20 monomer units (OPV-20). Time-dependent density functional theory calculations using the ωB97XD hybrid functional are employed in conjunction with a transition density analysis to study the low-lying singlet excitations and demonstrate that these can be characterized to a good approximation as a Frenkel exciton manifold. Based on these findings, we employ the analytic mapping procedure of Binder et al. [J. Chem. Phys. 141, 014101 (2014)] to translate one-dimensional (1D) and two-dimensional (2D) potential energy surface (PES) scans to a fully anharmonic, generalized Frenkel-Holstein (FH) Hamiltonian. A 1D PES scan is carried out for intra-ring quinoid distortion modes, while 2D PES scans are performed for the anharmonically coupled inter-monomer torsional and vinylene bridge bond length alternation modes. The kinetic energy is constructed in curvilinear coordinates by an exact numerical procedure, using the TNUM Fortran code. As a result, a fully molecular-based, generalized FH Hamiltonian is obtained, which is subsequently employed for quantum exciton dynamics simulations, as shown in Paper II [R. Binder and I. Burghardt, J. Chem. Phys. 152, 204120 (2020)].
基于包含20个单体单元的低聚物（OPV - 20）的激发态电子结构数据，构建了一个广义的弗伦克尔 - 霍尔斯坦哈密顿量，用于描述聚对苯撑乙烯链中的激子迁移。使用ωB97XD杂化泛函的含时密度泛函理论计算与跃迁密度分析相结合，研究低能单重激发，并证明这些激发可以很好地近似为弗伦克尔激子流形。基于这些发现，我们采用Binder等人[《化学物理杂志》141, 014101 (2014)]的解析映射程序，将一维（1D）和二维（2D）势能面（PES）扫描转换为完全非谐的广义弗伦克尔 - 霍尔斯坦（FH）哈密顿量。对环内醌式畸变模式进行一维PES扫描，同时对非谐耦合的单体间扭转和亚乙烯基桥键长交替模式进行二维PES扫描。动能通过精确的数值程序在曲线坐标中构建，使用TNUM Fortran代码。结果，得到了一个完全基于分子的广义FH哈密顿量，随后将其用于量子激子动力学模拟，如论文II [R. Binder和I. Burghardt，《化学物理杂志》152, 204120 (2020)]所示。
