A new extension of the polarizable continuum model: Toward a quantum chemical description of chemical reactions at extreme high pressure

2015 ◽  
Vol 36 (30) ◽  
pp. 2246-2259 ◽  
Author(s):  
Roberto Cammi
Keyword(s):  
High Pressure ◽  
Chemical Reactions ◽  
Quantum Chemical ◽  
Continuum Model ◽  
Polarizable Continuum Model ◽  
Polarizable Continuum ◽  
Chemical Description

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.

scholarly journals Quantum Chemistry for Molecules at Extreme Pressure on Graphical Processing Units: Implementation of Extreme Pressure Polarizable Continuum Model

2021 ◽  
Author(s):  
Ariel Gale ◽  
Eugen Hruska ◽  
Fang Liu
Keyword(s):  
High Pressure ◽  
Quantum Chemistry ◽  
Gas Phase ◽  
Continuum Model ◽  
Polarizable Continuum Model ◽  
Medium Size ◽  
Extreme Pressure ◽  
Graphical Processing Units ◽  
Graphical Processing ◽  
Polarizable Continuum

Pressure plays essential roles in chemistry by altering structures and controlling chemical reactions. The extreme-pressure polarizable continuum model (XP-PCM) is an emerging method with an efficient quantum mechanical description of small and medium-size molecules at high pressure (on the order of GPa). However, its application to large molecular systems was previously hampered by CPU computation bottleneck: the Pauli repulsion potential unique to XP-PCM requires the evaluation of a large number of electric field integrals, resulting in significant computational overhead compared to the gas-phase or standard-pressure polarizable continuum model calculations. Here, we exploit advances in Graphical Processing Units (GPUs) to accelerate the XP-PCM integral evaluations. This enables high-pressure quantum chemistry simulation of proteins that used to be computationally intractable. We benchmarked the performance using 18 small proteins in aqueous solutions. Using a single GPU, our method evaluates the XP-PCM free energy of a protein with over 500 atoms and 4000 basis functions within half an hour. The time taken by the XP-PCM-integral evaluation is typically 1\% of the time taken for a gas-phase density functional theory (DFT) on the same system. The overall XP-PCM calculations require less computational effort than that for their gas-phase counterpart due to the improved convergence of self-consistent field iterations. Therefore, the description of the high-pressure effects with our GPU accelerated XP-PCM is feasible for any molecule tractable for gas-phase DFT calculation. We have also validated the accuracy of our method on small molecules whose properties under high pressure are known from experiments or previous theoretical studies.

A simple heuristic approach to estimate the thermochemistry of condensed-phase molecules based on the polarizable continuum model

2019 ◽  
Vol 21 (35) ◽  
pp. 18920-18929 ◽  
Author(s):  
Yu-ichiro Izato ◽  
Akira Matsugi ◽  
Mitsuo Koshi ◽  
Atsumi Miyake
Keyword(s):  
Liquid Phase ◽  
Simple Model ◽  
Condensed Phase ◽  
Quantum Chemical ◽  
Continuum Model ◽  
Polarizable Continuum Model ◽  
Heuristic Approach ◽  
Continuum Models ◽  
Quantum Chemical Approach ◽  
Polarizable Continuum

A simple model based on a quantum chemical approach with polarizable continuum models (PCMs) to provide reasonable translational and rotational entropies for liquid phase molecules was developed.

scholarly journals High-pressure reaction profiles and activation volumes of 1,3-cyclohexadiene dimerizations computed by the extreme pressure-polarizable continuum model (XP-PCM)

2021 ◽  
Author(s):  
Bo Chen ◽  
K. N. Houk ◽  
Roberto Cammi
Keyword(s):  
High Pressure ◽  
Continuum Model ◽  
High Pressures ◽  
Polarizable Continuum Model ◽  
Activation Energies ◽  
Extreme Pressure ◽  
High Pressure Reaction ◽  
Experimental Values ◽  
Clear Shift ◽  
Polarizable Continuum

Quantum chemical calculations are reported for the thermal dimerizations of 1,3-cyclohexadiene at 1 atm and high pressures up to 6 GPa. Previous experiments [Klärner et al. Angew. Chem. Int. Ed. 1986, 25, 108], based on measured activation energies and activation volumes, suggested concerted mechanisms for the formation of the endo [4+2] cycloadduct and a [6+4]-ene adduct, and stepwise mechanisms for the formation of the exo [4+2] cycloadduct and two [2+2] cycloadducts. Computed activation enthalpies (ωB97XD, CCSD(T) and SC-NEVPT2) of plausible dimerization pathways at 1 atm agree well with the experiment activation energies and the values from previous calculations [Ess et al. J. Org. Chem. 2008, 73, 7586]. High-pressure reaction profiles, computed by the recently-developed extreme pressure-polarizable continuum model (XP-PCM), show that the reduction of reaction barrier is more profound in concerted reactions than in stepwise reactions, which is rationalized on the basis of the volume profiles of different mechanisms. A clear shift of the transition state towards the reactant by high pressure is revealed for the [6+4]-ene reaction by the calculations. The computed activation volumes by XP-PCM agree excellently with the experimental values, confirming the existence of competing mechanisms in the thermal dimerizations of 1,3-cyclohexadiene.

THEORETICAL STUDY ON HYDROLYSIS MECHANISM OF β-PHOSPHOLACTAMS

2006 ◽  
Vol 05 (spec01) ◽  
pp. 421-431 ◽  
Author(s):  
LINGJUAN YU ◽  
DACHENG FENG ◽  
MAOXIA HE ◽  
RUI LI ◽  
ZHENGTING CAI
Keyword(s):  
Quantum Chemical ◽  
Continuum Model ◽  
Chemical Method ◽  
Theoretical Study ◽  
Polarizable Continuum Model ◽  
Energy Barriers ◽  
Stepwise Mechanism ◽  
Hydrolysis Mechanism ◽  
Polarizable Continuum ◽  
Hydrolysis Of

The neutral hydrolysis mechanisms of a simple β-phospholactam with and without water-assisted reaction have been studied by using quantum chemical method at HF/6-31G**, MP2/6-31G** and B3LYP/6-31G** levels, respectively. The reaction can proceed by two different mechanisms: concerted and stepwise. There are two pathways in stepwise, i.e. pathway a and b, and the energy barriers of them are close. The energy barriers of water-assisted hydrolysis of β-phospholactam are obviously lower than those of no-water-assisted hydrolysis system. The energy barriers of stepwise mechanism are much lower than those of the concerted pathway in both cases. The solvent effects have been considered by means of a polarizable continuum model. The hydrolysis mechanism of β-phospholactam with that of the β-lactam and β-sultam was compared.

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