Electronic changes due to thermal disorder of hydrogen bonds in liquids: Pyridine in an aqueous environment

Fileti, Eudes Eterno; Coutinho, Kaline; Malaspina, Thaciana; Canuto, Sylvio

doi:10.1103/physreve.67.061504

Cited by 55 publications

(56 citation statements)

References 43 publications

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“…Recent results [20][21][22][23][24] showed that statistically converged results can be ensured by considering the autocorrelation functions of the energy in sampling the configurations from the liquid simulation. [20][21][22][23][24] In this work we revisit the chemical shift of liquid water using a sequential QM/MM methodology 21,23,24 and analyze how different functionals describe the chemical shielding in both gas and liquid phase. Other aspects will be considered, such as the dependence with the potential used in the simulations, the effects of molecular vibrations, the dependence with the selected clusters size.…”

Section: Introductionmentioning

confidence: 99%

Isotropic and anisotropic NMR chemical shifts in liquid water: a sequential QM/MM study

Fileti

Georg

Coutinho

et al. 2007

J. Braz. Chem. Soc.

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Apresentamos um estudo QM/MM seqüencial dos deslocamentos químicos gás-líquido da água. Cálculos de química quântica extensivos, usando a teoria do funcional da densidade foram realizados para estruturas do líquido de água, geradas através de simulações de Monte Carlo e Dinâmica Molecular. A dependência do deslocamento químico com os potenciais empíricos utilizados nas simulações, com o tamanho do aglomerado e com o funcional escolhido para os cálculos quânticos foi analisada. Os resultados corrigidos devido ao erro de superposição de base estão em boa concordância com os resultados experimentais, mostrando que um potencial empírico simples associado a um funcional apropriado é capaz de descrever os deslocamentos químicos. Todos os resultados apresentados são estatisticamente convergidos.We present a sequential QM/MM study of the gas-liquid chemical shifts of water. Extensive quantum chemical calculations using density functional theory have been performed for structures of liquid water generated by Monte Carlo and Molecular Dynamic simulations. The dependence of the chemical shifts on the empirical potential used in the simulations, on the cluster size and on the functional chosen for the quantum chemical calculations were analyzed. The results after correcting for basis set superposition errors are in good agreement with the experimental data, showing that a simple empirical potential associated to an appropriate functional is able to describe the chemical shifts. All results presented here are statistically converged. Keywords: sequential QM/MM, water, NMR, chemical shift, DFT IntroductionCalculations of the chemical shielding can reproduce with accuracy the chemical environment of the nuclei in a molecule. The advances in computational resources and the improvement in the theoretical methods provide important refinements to estimate the chemical shielding, such as inclusion of the electron correlation effects and the possibility of studying systems that are more complex than isolated molecules or small clusters. Presently the determination of the chemical shifts for nuclei in proteins, solids and liquids through current methodologies 1-5 are very convincing.An important category of systems whose electronic structure can be investigated through NMR calculations are solvated systems. A solvated molecule experiences the effect of the interaction with its vicinity, such as in hydrogen bonds. 6,7 Several theoretical models were proposed to describe the solvent effects on chemical shielding. [8][9][10][11][12][13][14] The main branches are the self-consistent reaction field methods (SCRF) 15,16 where the solute is placed inside a hollow cavity in a polarizable medium represented by its dielectric constant. In some cases, explicit solvent molecules, forming minimum energy clusters are considered in order to mimic the solvation shells of the solute. 10,17 It was shown that the former method does not work in determining the chemical shift and the latter, though it can serve as a rough approximation, does not serve as...

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Section: Introductionmentioning

confidence: 99%

Isotropic and anisotropic NMR chemical shifts in liquid water: a sequential QM/MM study

Fileti

Georg

Coutinho

et al. 2007

J. Braz. Chem. Soc.

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“…This gives the coordination of water molecules around the solute, but it cannot be assured that all near-neighbor water molecules are indeed hydrogen-bonded. This point has been the subject of previous concern [19,20,26,27,28]. The definition of a hydrogen bond in a liquid is not unanimously free from ambiguities.…”

Section: Hydrogen Bonds From Monte Carlo Simulationmentioning

confidence: 99%

“…In fact, a liquid is better described by statistical physics and its structure is represented by a great number of possible configurations or molecular arrangements. The thermal contribution leads to a decrease of the hydrogen bond interaction [19,20]. Hence, the strength of the hydrogen bond formed between methanol and water in gas phase is not the same as in the liquid case.…”

Section: Introductionmentioning

confidence: 99%

“…For the water molecules we use the SPC potential [23] and for methanol we use the all-site OPLS−AA potential [24]. Our sequential Monte Carlo/quantum mechanics procedure for generating liquid structure using MC simulation has been described previously in great detail [19,20,25,26]. The present simulation consisted of an equilibration stage of 2.0 × 10 6 MC steps, followed by a long averaging stage of 80.0 × 10 6 MC steps, where the equilibrium configurations are generated.…”

Section: Monte Carlo Simulationmentioning

confidence: 99%

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Is There a Favorite Isomer for Hydrogen-Bonded Methanol in Water?

Fileti¹,

Coutinho²,

Canuto³

2004

Advances in Quantum Chemistry

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Sequential Monte Carlo/Quantum Mechanical calculations of the interaction energy of hydrogen-bonded methanol in liquid water gives the same result for methanol acting either as the proton donor or the proton acceptor. For the complex-optimized cases methanol acting as the proton acceptor, CH 3 HO· · ·H 2 O, is more stable than the proton donor, CH 3 OH· · ·OH 2 , by ∼ 0.5 kcal/mol. In the case of methanol in liquid water, at room temperature, statistically converged results, using counterpoise corrected MP2/aug-cc-pVDZ calculations, leads to the same binding energy in both cases.

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“…We have also analyzed the acrolein-water hydrogen bonding by using geometrical criteria for the hydrogen bond. 86,87 We define the hydrogen bond between acrolein and a water molecule for R͓O͑acrolein͒ -O͑water͔͒ ഛ 3.18 Å and Є͓O͑acrolein͒ -O͑water͒ -H͑water͔͒ ഛ 45°. This definition of the hydrogen bond is based on the analysis of the O͑acrolein͒-O͑water͒ radial and O͑acrolein͒-O͑water͒-H͑water͒ angular distribution functions.…”

Section: Methodsmentioning

confidence: 99%

A subsystem density-functional theory approach for the quantum chemical treatment of proteins

Jacob

Visscher

2008

The Journal of Chemical Physics

136

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The performance of the Hartree-Fock method and the three density functionals B3LYP, PBE0, and CAM-B3LYP is compared to results based on the coupled cluster singles and doubles model in predictions of the solvatochromic effects on the vertical n → * and → * electronic excitation energies of acrolein. All electronic structure methods employed the same solvent model, which is based on the combined quantum mechanics/molecular mechanics approach together with a dynamical averaging scheme. In addition to the predicted solvatochromic effects, we have also performed spectroscopic UV measurements of acrolein in vapor phase and aqueous solution. The gas-to-aqueous solution shift of the n → * excitation energy is well reproduced by using all density functional methods considered. However, the B3LYP and PBE0 functionals completely fail to describe the → * electronic transition in solution, whereas the recent CAM-B3LYP functional performs well also in this case. The → * excitation energy of acrolein in water solution is found to be very dependent on intermolecular induction and nonelectrostatic interactions. The computed excitation energies of acrolein in vacuum and solution compare well to experimental data.

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Electronic changes due to thermal disorder of hydrogen bonds in liquids: Pyridine in an aqueous environment

Cited by 55 publications

References 43 publications

Isotropic and anisotropic NMR chemical shifts in liquid water: a sequential QM/MM study

Isotropic and anisotropic NMR chemical shifts in liquid water: a sequential QM/MM study

Is There a Favorite Isomer for Hydrogen-Bonded Methanol in Water?

A subsystem density-functional theory approach for the quantum chemical treatment of proteins

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