Modeling Optical Spectra of Large Organic Systems Using Real-Time Propagation of Semiempirical Effective Hamiltonians

Ghosh, Soumen; Andersen, Amity; Gagliardi, Laura; Cramer, Christopher J.; Govind, Niranjan

doi:10.1021/acs.jctc.7b00618

Cited by 23 publications

(25 citation statements)

References 151 publications

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“…These include C 60 , P3B2 which has been studied previously with real-time TDDFT [18] and semi-empirical methods [9] and ramoplanin (PDB code: 1DSR) which is an antibiotic drug. The computed spectra are shown in Figure 3 and have been computed using the 6-31G* basis set and PBE functional for C 60 and CAM-B3LYP functional for P3B2 and ramoplanin, and exclude the core orbitals and 70% of the virtual orbitals from the excitation subspace.…”

Section: Resultsmentioning

confidence: 99%

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Assessment of time-dependent density functional theory with the restricted excitation space approximation for excited state calculations of large systems

2018

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The restricted excitation subspace approximation is explored as a basis to reduce the memory storage required in linear response time-dependent density functional theory (TDDFT) calculations within the Tamm-Dancoff approximation. It is shown that excluding the core orbitals and up to 70% of the virtual orbitals in the construction of the excitation subspace does not result in significant changes in computed UV/vis spectra for large molecules. The reduced size of the excitation subspace greatly reduces the size of the subspace vectors that need to be stored when using the Davidson procedure to determine the eigenvalues of the TDDFT equations. Furthermore, additional screening of the twoelectron integrals in combination with a reduction in the size of the numerical integration grid used in the TDDFT calculation leads to significant computational savings. The use of these approximations represents a simple approach to extend TDDFT to the study of large systems and make the calculations increasingly tractable using modest computing resources.

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Section: Resultsmentioning

confidence: 99%

“…Other time-dependent semi-empirical approaches have been developed [7][8][9]. The low lying excited states of large systems have been studied with pseudo spectral TDDFT [10,11] which leads to a significant speedup in the calculations.…”

Section: Introductionmentioning

confidence: 99%

Assessment of time-dependent density functional theory with the restricted excitation space approximation for excited state calculations of large systems

2018

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“…76,[399][400][401] Recently, NWChem has also been interfaced with the SEMIEMP code, 402 which can be used to perform real-time electronic dynamics using the INDO/S Hamiltonian. 403,404…”

Section: A Interfacing With Other Softwarementioning

confidence: 99%

NWChem: Past, present, and future

Aprà

Bylaska

Jong

et al. 2020

The Journal of Chemical Physics

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523

289

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Specialized computational chemistry packages have permanently reshaped the landscape of chemical and materials science by providing tools to support and guide experimental efforts and for the prediction of atomistic and electronic properties. In this regard, electronic structure packages have played a special role by using first-principle-driven methodologies to model complex chemical and materials processes. Over the past few decades, the rapid development of computing technologies and the tremendous increase in computational power have offered a unique chance to study complex transformations using sophisticated and predictive many-body techniques that describe correlated behavior of electrons in molecular and condensed phase systems at different levels of theory. In enabling these simulations, novel parallel algorithms have been able to take advantage of computational resources to address the polynomial scaling of electronic structure methods. In this paper, we briefly review the NWChem computational chemistry suite, including its history, design principles, parallel tools, current capabilities, outreach, and outlook.

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“…Most of the widely-applied ab initio approaches for the calculation/prediction of observables measured by optical spectroscopies fall under the umbrella of time dependent electronic structure theories (TD-EST). Electronic excitation energies and associated transition probabilities probed by linear absorption spectroscopy can be accessed in TD-EST formalisms either through direct simulation of the electronic dynamics in the time domain, [1][2][3][4][5][6][7][8] or through application of response theory in the frequency domain. [9][10][11][12][13][14][15][16] Time-dependent self consistent field (TD-SCF) 17 methods, which include both time-dependent Hartree-Fock (TD-HF) and Kohn-Sham density functional theory (TD-DFT), are frequently employed in this context due to their favorable scaling with respect to system size.…”

Section: Introductionmentioning

confidence: 99%

First Principles Determination of Electronic Excitations Induced by Charged Particles

Lingerfelt

Ganesh²,

Jakowski³

et al. 2019

Preprint

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A time dependent self consistent field based method for determining the rates of electronic excitations induced in materials by the presence of external point charges is presented. The method utilizes the full scalar potential of the external point charge in the interaction Hamiltonian instead of relying on multipolar expansions thereof. A general method is presented for determining the conditions under which dipole selection rules are adequate to describe the electronic response of the material to perturbation by external point charges. The position dependence of point charge induced transition rates between the ground and lowest few excited electronic states was resolved for a small polybenzoid. Notably, electronic excitations that are optically forbidden can be strongly allowed for particular positions of the perturbing point charge. Application of the methods detailed here can lead to an improved understanding of the electronic response of materials under irradiation by beams of charged particles.

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Modeling Optical Spectra of Large Organic Systems Using Real-Time Propagation of Semiempirical Effective Hamiltonians

Cited by 23 publications

References 151 publications

Assessment of time-dependent density functional theory with the restricted excitation space approximation for excited state calculations of large systems

Assessment of time-dependent density functional theory with the restricted excitation space approximation for excited state calculations of large systems

NWChem: Past, present, and future

First Principles Determination of Electronic Excitations Induced by Charged Particles

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