Mancal Tomás, Pisliakov Andrei V, Fleming Graham R
Department of Chemistry, University of California-Berkeley, Berkeley, CA 94720, USA.
J Chem Phys. 2006 Jun 21;124(23):234504. doi: 10.1063/1.2200704.
The nonperturbative approach to the calculation of nonlinear optical spectra of Seidner et al. [J. Chem. Phys. 103, 3998 (1995)] is extended to describe four-wave mixing experiments. The system-field interaction is treated nonperturbatively in the semiclassical dipole approximation, enabling a calculation of third order nonlinear spectroscopic signals directly from molecular dynamics and an efficient modeling of multilevel systems exhibiting relaxation and transfer phenomena. The method, coupled with the treatment of dynamics within the Bloch model, is illustrated by calculations of the two-dimensional three-pulse photon echo spectra of a simple model system-a two-electronic-level molecule. The nonperturbative calculations reproduce well-known results obtained by perturbative methods. Technical limitations of the nonperturbative approach in dealing with a dynamic inhomogeneity are discussed, and possible solutions are suggested. An application of the approach to an excitonically coupled dimer system with emphasis on the manifestation of complex exciton dynamics in two-dimensional optical spectra is presented in paper II Pisliakov et al. [J. Chem. Phys. 124, 234505 (2006), following paper].
Seidner等人[《化学物理杂志》103, 3998 (1995)]计算非线性光学光谱的非微扰方法被扩展用于描述四波混频实验。在半经典偶极近似中对系统 - 场相互作用进行非微扰处理，从而能够直接从分子动力学计算三阶非线性光谱信号，并对表现出弛豫和转移现象的多能级系统进行有效建模。通过对一个简单模型系统——双电子能级分子的二维三脉冲光子回波光谱进行计算，说明了该方法与布洛赫模型内动力学处理的结合。非微扰计算重现了微扰方法得到的众所周知的结果。讨论了非微扰方法在处理动态不均匀性方面的技术局限性，并提出了可能的解决方案。该方法在一个激子耦合二聚体系统中的应用，重点是二维光谱中复杂激子动力学的表现，将在论文II（Pisliakov等人[《化学物理杂志》124, 234505 (2006)，后续论文]）中给出。
