Jones and magnetoelectric birefringence of pure substances — A computational study

2009 ◽  
Vol 87 (10) ◽  
pp. 1352-1361 ◽  
Author(s):  
Antonio Rizzo ◽  
Dmitry Shcherbin ◽  
Kenneth Ruud
Keyword(s):  
Condensed Phase ◽  
Continuum Model ◽  
Density Functional ◽  
Computational Study ◽  
Polarizable Continuum Model ◽  
Solvent Interactions ◽  
Dipolar Molecules ◽  
Upper Limits ◽  
Order Of Magnitude ◽  
Polarizable Continuum

We present the first investigation of condensed-phase effects on the Jones (and magnetoelectric) birefringence of a set of nondipolar (CCl4 and CS2) and dipolar (nitro- and chloro-benzene) molecules using a recent implementation of the polarizable continuum model for cubic response functions at the time-dependent density-functional level of theory. The condensed-phase calculations have been performed on the neat liquids of the sample molecules using a nonequilibrium solvation scheme to properly account for the solute–solvent interactions in the presence of a frequency-dependent electromagnetic field. It is demonstrated that the condensed-phase effects as modelled by the polarizable continuum model can be substantial, increasing the observable birefringence by more than sixty percent in the case of CCl4, and by a factor of more than three for CS2. Solvent effects are also substantial for the dipolar molecules, leading to an enhancement by a factor of roughly five for nitrobenzene and by a bit less than 30% for chlorobenzene. Comparison is made with the results of experiment. Our calculated anisotropies confirm that the effect is below current experimental detection limits for CCl4 and CS2. We compute Jones constants of the same order of magnitude as the upper limits given in experiment for nitro- and chlorobenzene.

scholarly journals Н-комплексы 1,2-нафтохинона с молекулами воды в водном растворе и их влияние на сдвиги полос поглощения

2021 ◽  
Vol 129 (5) ◽  
pp. 599
Author(s):  
С.Н. Цеплина ◽  
E.E. Цеплин
Keyword(s):  
Quantum Chemical ◽  
Continuum Model ◽  
Density Functional ◽  
Water Solution ◽  
Polarizable Continuum Model ◽  
Water Molecules ◽  
Absorption Bands ◽  
Functional Theory ◽  
Polarizable Continuum ◽  
Polar Water

Optical absorption spectra of 1,2-naphthoquinone in non-polar (n-hexane) and polar (water) solvents were obtained. It is shown that the use of quantum chemical calculations based on time-dependent density functional theory (TDDFT B3LYP/6-311+G(d, p)) with the polarizable continuum model (PCM) for calculating 1,2-naphthoquinone in a solution of n-hexane and hydrogen complex of 1,2-naphthoquinone with two water molecules in an aqueous medium describes well the shifts of the absorption bands of 1,2-naphthoquinone in a water solution compared to a solution in n-hexane. Based on the analysis of deviations of the calculated band shifts from the experimental ones, the question of the formation of 1,2-naphthoquinone hydrogen complexes with n water molecules (n = 1-4) in an aqueous solution is considered.

The fragment molecular orbital method combined with density-functional tight-binding and the polarizable continuum model

2016 ◽  
Vol 18 (32) ◽  
pp. 22047-22061 ◽  
Author(s):  
Yoshio Nishimoto ◽  
Dmitri G. Fedorov
Keyword(s):  
Molecular Structure ◽  
Molecular Orbital ◽  
Continuum Model ◽  
Density Functional ◽  
Tight Binding ◽  
Polarizable Continuum Model ◽  
Orbital Method ◽  
Molecular Orbital Method ◽  
Polarizable Continuum ◽  
Structure Of Proteins

The electronic gap in proteins is analyzed in detail, and it is shown that FMO-DFTB/PCM is efficient and accurate in describing the molecular structure of proteins in solution.

THEORETICAL STUDY OF GLYCINE CONFORMERS

2008 ◽  
Vol 07 (04) ◽  
pp. 889-909 ◽  
Author(s):  
HONG-WEI KE ◽  
LI RAO ◽  
XIN XU ◽  
YI-JING YAN
Keyword(s):  
Potential Energy Surfaces ◽  
Density Functional ◽  
Polarizable Continuum Model ◽  
Basis Sets ◽  
Dft Methods ◽  
Solvent Interactions ◽  
Solvation Effects ◽  
Moller Plesset ◽  
Energy Surfaces ◽  
Polarizable Continuum

Glycine conformers were investigated with three density functional theory (DFT) methods (B3LYP, PBE1PBE, X3LYP), and the second order Møller–Plesset perturbation theory (MP2) combined with basis sets of 6-31+G*, aug-cc-pVDZ, and aug-cc-pVTZ. Solvation effects were considered by using polarizable continuum model. Results from B3LYP and X3LYP were in generally good agreement with those of MP2, while PBE1PBE was shown to be inferior for the description of conformational potential energy surfaces. Conformers Ip, IIp, IIn, IIIp, IIIn, and IVn were all found to be low-lying states within 2.0 kcal/mol, with Ip being the global minimum in gas phase. Solvation effects can significantly change the nature of the conformational surfaces of glycine. A proper description of conformational equilibrium demands for a good treatment of both long-range and short-range solute–solvent interactions.

scholarly journals Time-Dependent Long-Range Corrected Density-Functional Tight-Binding Method Combined with the Polarizable Continuum Model

2019 ◽  
Author(s):  
Yoshio Nishimoto
Keyword(s):  
Excited State ◽  
Long Range ◽  
Continuum Model ◽  
Density Functional ◽  
Tight Binding ◽  
Polarizable Continuum Model ◽  
Time Dependent ◽  
Dual Emission ◽  
Tight Binding Method ◽  
Polarizable Continuum

In this study, excited-state free energies and geometries were efficiently evaluated using a linear-response time-dependent long-range corrected density-functional tight-binding method integrated with the polarizable continuum model (TD-LC-DFTB/PCM). Although the LC-DFTB method required the evaluation of the exchange-type term, which was moderately computationally expensive, a single evaluation of the excited-state gradient for a system consisting of more than 1000 atoms in a vacuum was completed within 30 minutes using one CPU core. Benchmark calculations were conducted for 3-hydroxy avone, which exhibits dual emission: the absorption and enol-form emission wavelengths calculated by TD-LC-DFTB/PCM agreed well with those predicted based on density functional theory using a long-range corrected functional; however, there was a large error in the predicted keto-form emission wavelength. Further benchmark calculations for more than 20 molecules indicated that the conventional TD-DFTB method underestimated the absorption and 0-0 transition energies compared with those which were measured experimentally while the TD-LC-DFTB method systematically overestimated these metrics. Nevertheless, the agreement of the results of the TD-LC-DFTB method with those obtained by the CAM-B3LYP method demonstrates the potential of the TD-LC-DFTB/PCM method. Moreover, changing the range-separation parameter to 0.15 minimized this deviation.<br>

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