CAST: A new program package for the accurate characterization of large and flexible molecular systems

Grebner, Christoph; Becker, Johannes; Weber, Daniel K.; Bellinger, Daniel; Tafipolski, Maxim; Brückner, Charlotte; Engels, Bernd

doi:10.1002/jcc.23687

Cited by 5 publications

(4 citation statements)

References 64 publications

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“…The solvent shell was pre‐optimized for the neutral, the cationic and the anionic monomer structures using the AMOEBA09 force field in combination with different global optimization techniques like Tabu Search and Basin Hopping . These calculations were performed with the CAST program. In a second step the global minima of the solvent shells were locally optimized by using the BP86/TZV(P) method within Turbomole 6.6.…”

Section: Theoretical Methods and Technical Detailsmentioning

confidence: 99%

Influence of a polarizable surrounding on the electronically excited states of aggregated perylene materials

et al. 2016

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To tune the efficiency of organic semiconductor devices it is important to understand limiting factors as trapping mechanisms for excitons or charges. An understanding of such mechanisms deserves an accurate description of the involved electronical states in the given environment. In this study, we investigate how a polarizable surrounding influences the relative positions of electronically excited states of dimers of different perylene dyes. Polarization effects are particularly interesting for these systems, because gas phase computations predict that the CT states lie slightly above the corresponding Frenkel states. A polarizable environment may change this energy order because CT states are thought to be more sensitive to a polarizable surrounding than Frenkel states. A first insight we got via a TD-HF approach in combination with a polarizable continuum model (PCM). These give limited insights because TD-HF overestimates excitation energies of CT states. However, SCS-CC2 approaches, which are sufficiently accurate, cannot easily be used in combination with continuum solvent models. Hence, we developed two approaches to combine gas phase SCS-CC2 results with solvent effects based on TD-HF computations. Their accuracies were finally checked via ADC(2)//COSMO computations. The results show that for perylene dyes a polarizable surrounding alone does not influence the energetic ordering of CT and Frenkel states. Variations in the energy order of the states only result from nuclear relaxation effects after the excitation process. © 2016 Wiley Periodicals, Inc.

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Section: Theoretical Methods and Technical Detailsmentioning

confidence: 99%

Influence of a polarizable surrounding on the electronically excited states of aggregated perylene materials

et al. 2016

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“…To simulate the a-PTCDA environment, we employ the AMOEBA polarizable force field 103 while a new force field had to be developed for DIP. [104][105][106] For the computation of the inner dimer we used the SCS-CC2 approach, 107 because multi-reference configuration interaction calculations 108,109 are way too expensive for the given systems.…”

Section: Exciton Diffusion Lengths: A-ptcda Versus Dipmentioning

confidence: 99%

The dimer-approach to characterize opto-electronic properties of and exciton trapping and diffusion in organic semiconductor aggregates and crystals

Engels

Engel

2017

Phys. Chem. Chem. Phys.

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A fundamental understanding of photo-induced processes in opto-electronic thin film devices is a prerequisite for the rational design of improved organic semiconductor materials. Absorption and emission spectra provide important insights into the complicated electronic structure of and relaxation processes in organic semiconductor aggregates and crystals. They are of interest because they often limit the efficiencies of the devices. For an assignment of the spectra a close interplay between experiment and theory is essential because simulations are often necessary to entangle the various effects which determine the features of the spectra. In the present perspective we describe the so called dimer-approach and provide a few examples in which this approach could successfully deliver an atomistic picture of photo-induced relaxation effects in perylene-based materials and characterize their optical spectra. The model Hamiltonians of standard monomer-based approaches are also briefly discussed to reveal the differences between both methods and to shed some light on their strengths and shortcomings.

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“…The strategy of the present method might be similar to that of the original Tabu Search (TB) , and its variants. − TB utilizes the steepest descent–modest ascent strategy. The steepest descent is useful for finding the next local minimum.…”

Section: Introductionmentioning

confidence: 99%

Self-Avoiding Conformational Sampling Based on Histories of Past Conformational Searches

Harada

Shigeta

2017

J. Chem. Inf. Model.

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Self-avoiding conformational sampling (SACS) is proposed as an enhanced conformational sampling method for proteins. In SACS, the following conformational resampling is repeated for a given protein: (1) identification of newly visited states in a subspace and (2) conformational resampling by restarting short-time molecular dynamics (MD) simulations from the newly visited states. To identify the newly visited states, a set of history-dependent histograms projected onto the subspace is used. One is constructed from the trajectories sampled at the current (ith) cycle, and the other is constructed from all of the trajectories accumulated up through the previous ((i - 1)th) cycle. By reference to the history-dependent histograms, the newly visited states appearing at the current (ith) cycle are defined as a difference set between them. By repeating the cycle of conformational resampling, SACS prevents the system from revisiting states that have already been visited for previous cycles, promoting structural transitions via resampling from the newly visited states. To verify the conformational sampling efficiency of SACS, the present method was applied to reveal underlying mechanisms of biologically important domain motions of maltodextrin binding protein in explicit water and successfully reproduced the open-closed transition with a reasonable (nanosecond-order) computational cost.

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CAST: A new program package for the accurate characterization of large and flexible molecular systems

Cited by 5 publications

References 64 publications

Influence of a polarizable surrounding on the electronically excited states of aggregated perylene materials

Influence of a polarizable surrounding on the electronically excited states of aggregated perylene materials

The dimer-approach to characterize opto-electronic properties of and exciton trapping and diffusion in organic semiconductor aggregates and crystals

Self-Avoiding Conformational Sampling Based on Histories of Past Conformational Searches

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