Mind the correct basis set: A case study for predicting gas phase acidities of small compounds using calculations from first principles

2014 ◽  
Vol 115 (1) ◽  
pp. 42-49 ◽  
Author(s):  
Nina Tymińska ◽  
Marta Włoch ◽  
A. Timothy Royappa
Keyword(s):  
Gas Phase ◽  
First Principles ◽  
Basis Set

Reactions in solution

2018 ◽  
Author(s):  
Dennis Sherwood ◽  
Paul Dalby
Keyword(s):  
Phase Equilibria ◽  
Gas Phase ◽  
First Principles ◽  
Unique Feature ◽  
Life Sciences ◽  
Equilibrium Mixture ◽  
Second Law ◽  
Ideal Solution ◽  
Coupled Reactions ◽  
Definition Of

Another key chapter, examining reactions in solution. Starting with the definition of an ideal solution, and then introducing Raoult’s law and Henry’s law, this chapter then draws on the results of Chapter 14 (gas phase equilibria) to derive the corresponding results for equilibria in an ideal solution. A unique feature of this chapter is the analysis of coupled reactions, once again using first principles to show how the coupling of an endergonic reaction to a suitable exergonic reaction results in an equilibrium mixture in which the products of the endergonic reaction are present in much higher quantity. This demonstrates how coupled reactions can cause entropy-reducing events to take place without breaking the Second Law, so setting the scene for the future chapters on applications of thermodynamics to the life sciences, especially chapter 24 on bioenergetics.

scholarly journals First principles characterisation of bio–nano interface

2021 ◽  
Author(s):  
Ian Rouse ◽  
David Power ◽  
Erik G. Brandt ◽  
Matthew Schneemilch ◽  
Konstantinos Kotsis ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
First Principles ◽  
Computational Approach ◽  
Titania Nanoparticles ◽  
Coarse Grained ◽  
First Principles Study

We present a multiscale computational approach for the first-principles study of bio-nano interactions. Using titanium dioxide as a case study, we evaluate the affinity of titania nanoparticles to water and biomolecules through atomistic and coarse-grained techniques.

Pros and cons of time-dependent hybrid density functional approach to optical spectra of solids: a case study of CeO2

2021 ◽  
Author(s):  
Huai-Yang Sun ◽  
Shuo-Xue Li ◽  
Hong Jiang
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Computational Cost ◽  
Optical Spectra ◽  
First Principles Calculation ◽  
Many Body ◽  
Many Body Perturbation Theory ◽  
Pros And Cons ◽  
Hybrid Density Functional

Prediction of optical spectra of complex solids remains a great challenge for first-principles calculation due to the huge computational cost of the state-of-the-art many-body perturbation theory based GW-Bethe Salpeter equation...

scholarly journals Absorption mechanism, structural and electronic properties of MC19 (M = B and Si) fullerenes with 1-acetylpiperazine

2017 ◽  
Vol 36 (1-2) ◽  
pp. 797-804
Author(s):  
Özgür Alver ◽  
Cemal Parlak ◽  
Mohamed I Elzagheid ◽  
Ponnadurai Ramasami
Keyword(s):  
Electronic Properties ◽  
Gas Phase ◽  
Basis Set ◽  
Stable Complex ◽  
Absorption Mechanism ◽  
Boron Doped ◽  
Structural And Electronic Properties ◽  
Influence Of Water ◽  
Vibrational Bands ◽  
Silicon Doped

The interaction mechanisms of undoped, silicon- and boron-doped C20 fullerenes and 1-acetylpiperazine (1-ap) were investigated. Stability, electronic properties, influence of water on the solubility and stability, molecular parameters, descriptive vibrational bands and nuclear magnetic resonance shielding values are reported. The quantum mechanical calculations were carried out using the M06-2X functional and the 6-31G(d) basis set. It is observed that all the complexes are more stabilized in water compared to the gas phase. The most stable complex was found as silicon-doped fullerene interacting with the carbonyl edge of 1-ap releasing energy of 64.13 kcal/mol in water.

scholarly journals Unknown Knowns: Case Studies in Uncertainties in the Computation of Thermochemical Parameters

2020 ◽  
Author(s):  
John Simmie
Keyword(s):  
Heat Capacity ◽  
Gas Phase ◽  
Basis Set ◽  
Statistical Thermodynamic ◽  
Vibrational Modes ◽  
Heavy Atoms ◽  
New Methods ◽  
Formation Enthalpies ◽  
Thermochemical Parameters

<div>Both the computation of, and the uncertainties associated, with gas-phase molar formation enthalpies are now quite well established for systems comprised of tens of ‘heavy’ atoms chosen from the commonest elements. The same cannot be said for derived thermochemical quantities such as entropy, heat capacity and an enthalpy function. Whilst the application of well known statistical thermodynamic relations is mostly understood, the determination of the uncertainty with which such values can be obtained has been little studied — apart, that is, for a general protocol devised by Goldsmith et al. [J. Phys. Chem. A, 2012, 116, 9033–9057]. Specific examples from that work are explored here and it is shown that their estimates are overly pessimistic. It is also evident that for some species the calculated thermochemical parameters show very little variation with either the level of theory, or basis set, or treatment of vibrational modes — this renders the inclusion of such species in databases designed to validate new methods of limited value.<br></div>

scholarly journals Modeling organic aerosols in a megacity: comparison of simple and complex representations of the volatility basis set approach

2010 ◽  
Vol 10 (12) ◽  
pp. 30205-30277 ◽  
Author(s):  
M. Shrivastava ◽  
J. Fast ◽  
R. Easter ◽  
W. I. Gustafson ◽  
R. A. Zaveri ◽  
...  
Keyword(s):  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Computational Cost ◽  
Organic Aerosols ◽  
Field Measurements ◽  
Organic Aerosol ◽  
Basis Set ◽  
Aerosol Formation ◽  
Secondary Organic Aerosol Formation ◽  
The City

Abstract. The Weather Research and Forecasting model coupled with chemistry (WRF-Chem) is modified to include a volatility basis set (VBS) treatment of secondary organic aerosol formation. The VBS approach, coupled with SAPRC-99 gas-phase chemistry mechanism, is used to model gas-particle partitioning and multiple generations of gas-phase oxidation of organic vapors. In addition to the detailed 9-species VBS, a simplified mechanism using 2 volatility species (2-species VBS) is developed and tested for similarity to the 9-species VBS in terms of both mass and oxygen-to-carbon ratios of organic aerosols in the atmosphere. WRF-Chem results are evaluated against field measurements of organic aerosols collected during the MILAGRO 2006 campaign in the vicinity of Mexico City. The simplified 2-species mechanism reduces the computational cost by a factor of 2 as compared to 9-species VBS. Both ground site and aircraft measurements suggest that the 9-species and 2-species VBS predictions of total organic aerosol mass as well as individual organic aerosol components including primary, secondary, and biomass burning are comparable in magnitude. In addition, oxygen-to-carbon ratio predictions from both approaches agree within 25%, providing evidence that the 2-species VBS is well suited to represent the complex evolution of organic aerosols. Model sensitivity to amount of anthropogenic semi-volatile and intermediate volatility (S/IVOC) precursor emissions is also examined by doubling the default emissions. Both the emission cases significantly under-predict primary organic aerosols in the city center and along aircraft flight transects. Secondary organic aerosols are predicted reasonably well along flight tracks surrounding the city, but are consistently over-predicted downwind of the city. Also, oxygen-to-carbon ratio predictions are significantly improved compared to prior studies by adding 15% oxygen mass per generation of oxidation; however, all modeling cases still under-predict these ratios downwind as compared to measurements, suggesting a need to further improve chemistry parameterizations of secondary organic aerosol formation.

scholarly journals Using first-principles calculations to screen for fragile magnetism: Case study of LaCrGe3 and LaCrSb3

2018 ◽  
Vol 97 (18) ◽  
Author(s):  
Manh Cuong Nguyen ◽  
Valentin Taufour ◽  
Sergey L. Bud'ko ◽  
Paul C. Canfield ◽  
Vladimir P. Antropov ◽  
...  
Keyword(s):  
First Principles ◽  
First Principles Calculations

Donor Functionalized Perylene and Different π-Spacers Based Sensitizers for DSSC Applications - A Theoretical Approach

2021 ◽  
Author(s):  
D. Nicksonsebastin ◽  
P. Pounraj ◽  
Prasath M
Keyword(s):  
Density Functional Theory ◽  
Solar Cell ◽  
Gas Phase ◽  
Density Functional ◽  
Basis Set ◽  
Dye Sensitized Solar Cell ◽  
Functional Theory ◽  
Dye Sensitized ◽  
Td Dft ◽  
Organic Sensitizers

Abstract Perylene based novel organic sensitizers for the Dye sensitized solar cell applications are investigated by using Density functional theory (DFT) and time dependant density functional theory (TD-DFT).The designed sensitizers have perylene and dimethylamine (DM) and N-N-dimethylaniline(DMA) functionalized perylene for the dssc applications.π-spacers are thiophene andcyanovinyl groups and cyanoacrylic acid is chosen as the acceptor for the designed sensitizers. The studied sensitizers were fully optimized by density functional theory at B3LYP/6-311G basis set on gas phase and DMF phase. The electronic absorption of the sensitizers is analyzed by TD-DFT at B3LYP/6-311G basis set in both gas and DMF phase.

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