No data available.

Please log in to see this content.

You have no subscription access to this content.

No metrics data to plot.

The attempt to load metrics for this article has failed.

The attempt to plot a graph for these metrics has failed.

Efficient and automatic calculation of optical band shapes and resonance Raman spectra for larger molecules within the independent mode displaced harmonic oscillator model

Rent:

Rent this article for

USD

10.1063/1.4771959

### Abstract

In this work, an improved method for the efficient automatic simulation of optical band shapes and resonance Raman (rR) intensities within the “independent mode displaced harmonic oscillator” is described. Despite the relative simplicity of this model, it is able to account for the intensity distribution in absorption (ABS), fluorescence, and rR spectra corresponding to strongly dipole allowed electronic transitions with high accuracy. In order to include temperature-induced effects, we propose a simple extension of the time dependent wavepacket formalism developed by Heller which enables one to derive analytical expressions for the intensities of hot bands in ABS and rR spectra from the dependence of the wavepacket evolution on its initial coordinate. We have also greatly optimized the computational procedures for numerical integration of complicated oscillating integrals. This is important for efficient simulations of higher-order rR spectra and excitation profiles, as well as for the fitting of experimental spectra of large molecules. In particular, the multimode damping mechanism is taken into account for efficient reduction of the upper time limit in the numerical integration. Excited stateenergy gradient as well as excited state geometry optimization calculations are employed in order to determine excited state dimensionless normal coordinate displacements. The gradient techniques are highly cost-effective provided that analytical excited state derivatives with respect to nuclear displacements are available. Through comparison with experimental spectra of some representative molecules, we illustrate that the gradient techniques can even outperform the geometry optimization method if the harmonic approximation becomes inadequate.

© 2012 American Institute of Physics

Received 28 March 2012
Accepted 26 November 2012
Published online 20 December 2012

Acknowledgments: We gratefully acknowledge the financial support of this work by the Max-Planck Gesellschaft and the University of Bonn.

Article outline:

I. INTRODUCTION

II. THEORY

A. Fundamental equations

B. Short-time approach for efficient spectral simulation procedures

C. Prescreening conditions for selecting Raman transitions and initial vibrational states

D. Quantum chemical calculations of harmonic model parameters

III. NUMERICAL CALCULATIONS

A. Computational details

B. Absorption and resonance Raman spectra for (1^{1}A_{g} →1^{1}B_{u}) transition of trans-1,3,5-hexatriene

C. Absorption and fluorescence spectra for S_{0}→S_{1} transition in tetracene and rubrene

D. Absorption and resonance Raman spectra for intervalence charge transfer (IVCT) transitions in [Ni(L)_{2}]^{1−} (L = benzene-1,2-dithiol)

E. Importance of thermal effects in resonance Raman spectra

F. Efficiency of TDDFT excited state gradient calculations and spectral simulation procedures

IV. CONCLUSIONS

/content/aip/journal/jcp/137/23/10.1063/1.4771959

http://aip.metastore.ingenta.com/content/aip/journal/jcp/137/23/10.1063/1.4771959

Article metrics loading...

/content/aip/journal/jcp/137/23/10.1063/1.4771959

2012-12-20

2014-04-17

Full text loading...

### Most read this month

Article

content/aip/journal/jcp

Journal

5

3

Commenting has been disabled for this content