Potential energy landscape for proton transfer in (H2O)3H+: comparison of density functional theory and wavefunction-based methods

2000 ◽  
Vol 324 (1-3) ◽  
pp. 149-155 ◽  
Author(s):  
Phillip L Geissler ◽  
Troy Van Voorhis ◽  
Christoph Dellago
Keyword(s):  
Density Functional Theory ◽  
Potential Energy ◽  
Proton Transfer ◽  
Density Functional ◽  
Energy Landscape ◽  
Functional Theory ◽  
Potential Energy Landscape

scholarly journals Minimal Optimized Effective Potentials for Density Functional Theory Studies on Excited-State Proton Dissociation

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 679
Author(s):  
Pouya Partovi-Azar ◽  
Daniel Sebastiani
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Proton Transfer ◽  
Density Functional ◽  
Photochemical Reactions ◽  
Transfer Energy ◽  
Functional Theory ◽  
Effective Potentials ◽  
Proton Dissociation ◽  
Dissociation Curves

Recently, a new method [P. Partovi-Azar and D. Sebastiani, J. Chem. Phys. 152, 064101 (2020)] was proposed to increase the efficiency of proton transfer energy calculations in density functional theory by using the T1 state with additional optimized effective potentials instead of calculations at S1. In this work, we focus on proton transfer from six prototypical photoacids to neighboring water molecules and show that the reference proton dissociation curves obtained at S1 states using time-dependent density functional theory can be reproduced with a reasonable accuracy by performing T1 calculations at density functional theory level with only one additional effective potential for the acidic hydrogens. We also find that the extra effective potentials for the acidic hydrogens neither change the nature of the T1 state nor the structural properties of solvent molecules upon transfer from the acids. The presented method is not only beneficial for theoretical studies on excited state proton transfer, but we believe that it would also be useful for studying other excited state photochemical reactions.

THE H2NO POTENTIAL ENERGY SURFACE EXPLORED WITH HIGH LEVEL AB INITIO AND DENSITY FUNCTIONAL THEORY METHODS

2007 ◽  
Vol 06 (03) ◽  
pp. 549-562
Author(s):  
ABRAHAM F. JALBOUT
Keyword(s):  
Density Functional Theory ◽  
Potential Energy ◽  
Potential Energy Surface ◽  
Density Functional ◽  
Energy Surface ◽  
Hybrid Methods ◽  
Transition States ◽  
Basis Set ◽  
Functional Theory ◽  
High Level

The transition states for the H 2 NO decomposition and rearrangements mechanisms have been explored by the CBS-Q method or by density functional theory. Six transition states were located on the potential energy surface, which were explored with the Quadratic Complete Basis Set (CBS-Q) and Becke's one-parameter density functional hybrid methods. Interesting deviations between the CBS-Q results and the B1LYP density functional theory lead us to believe that further study into this system is necessary. In the efforts to further assess the stabilities of the transition states, bond order calculations were performed to measure the strength of the bonds in the transition state.

Elimination of AgR (R = H, CH3, C6H5) from Collisionally-Activated Argentinated Amines

2000 ◽  
Vol 6 (2) ◽  
pp. 187-192 ◽  
Author(s):  
R. Natasha Grewal ◽  
Christopher F. Rodriquez ◽  
Tamer Shoeib ◽  
Ivan K. Chu ◽  
Ya-Ping Tu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Potential Energy ◽  
Density Functional ◽  
Amino Nitrogen ◽  
Functional Theory ◽  
Immonium Ions

Fragmentation of collisionally-activated argentinated amines results in the formation of Ag+ and non-silver-containing ions. The latter are likely immonium ions that are formed after elimination of AgH and, when the ion structures permit, AgCH3 or AgC6H5. The H, CH3 and C6H5 groups are attached to the carbon alpha to the amino nitrogen, and are believed to be cleaved with the Ag in a 1,2-elimination. This hypothesis is supported by potential energy hypersurfaces calculated using density functional theory for the reactions involving methanamine and ethanamine.

scholarly journals Decomposition of Formic Acid over Orthorhombic Molybdenum Carbide

2021 ◽  
Author(s):  
Kushagra Agrawal ◽  
Alberto Roldan ◽  
Nanda Kishore ◽  
Andrew J Logsdail
Keyword(s):  
Formic Acid ◽  
Density Functional ◽  
Molybdenum Carbide ◽  
Catalyst Surface ◽  
Energy Landscape ◽  
Functional Theory ◽  
Potential Energy Landscape ◽  
Temperature Programmed ◽  
Temperature Programmed Reaction ◽  
Dehydrogenation Mechanism

The decomposition of formic acid is investigated on the β-Mo<sub>2</sub>C (100) catalyst surface using density functional theory. The dehydration and dehydrogenation mechanism for the decomposition is simulated, and the thermochemistry and kinetics are discussed. The potential energy landscape of the reaction shows a thermodynamically favourable cleavage of H-COOH to form CO; however, the kinetics show that the dehydrogenation mechanism is faster and CO<sub>2</sub> is continuously formed. The effect of HCOOH adsorption on the surface is also analysed, in a temperature-programmed reaction, with the decomposition proceeding at under 350 K and desorption of CO<sub>2</sub> observed.

Catalysis with a Skip: Dynamically Coupled Addition, Proton Transfer, and Elimination During Au- and Pd-Catalyzed Diol Cyclization

2021 ◽  
Author(s):  
Matthew Teynor ◽  
Windsor Scott ◽  
Daniel Ess
Keyword(s):  
Potential Energy ◽  
Proton Transfer ◽  
Energy Landscape ◽  
Cyclization Reactions ◽  
Potential Energy Landscape ◽  
Water Elimination ◽  
Catalytic Intermediates ◽  
Pd Complexes ◽  
Dynamics Simulations ◽  
Step Mechanism

Au and Pd complexes have emerged as highly effective π-bond cyclization catalysts to construct heterocycles. These cyclization reactions are generally proposed to proceed through multi-step addition-elimination mechanisms involving Au- or Pd-alkyl intermediates. For Au- and Pd-catalyzed allylic diol cyclization, while the DFT potential energy surface landscapes show a stepwise sequence of alkoxylation π-addition, proton transfer, and water elimination, quasiclassical direct dynamics simulations reveal new dynamical mechanisms that depend on the metal center. For Au, trajectories reveal that after π-addition the Au-alkyl intermediate is always skipped because addition is dynamically coupled with proton transfer and water elimination. In contrast, for Pd catalysis, due to differences in the potential-energy landscape shape, only about half of trajectories show Pd-alkyl intermediate skipping. The other half of the trajectories show the traditional two-step mechanism with the intervening Pd-alkyl intermediate. Overall, this work reveals that interpretation of a DFT potential-energy landscape can be insufficient to understand catalytic intermediates and mechanisms and that atomic momenta through dynamics simulations is needed to determine if an intermediate is genuinely part of a catalytic cycle.<br>

scholarly journals Double-well potential energy surface in the interaction between h-BN and Ni(111)

2019 ◽  
Vol 21 (21) ◽  
pp. 10888-10894
Author(s):  
Jorge Ontaneda ◽  
Francesc Viñes ◽  
Francesc Illas ◽  
Ricardo Grau-Crespo
Keyword(s):  
Density Functional Theory ◽  
Potential Energy ◽  
Density Functional ◽  
Energy Surface ◽  
Density Functional Theory Calculations ◽  
Dispersion Forces ◽  
Local Correlation ◽  
Functional Theory ◽  
Non Local ◽  
Double Well Potential

Density functional theory calculations with non-local correlation functionals, properly accounting for dispersion forces, predict the presence of two minima in the interaction energy between h-BN and Ni(111).

scholarly journals Influence of Varying Functionalization on the Peroxidase Activity of Nickel(II)–Pyridine Macrocycle Catalysts: Mechanistic Insights from Density Functional Theory

Computation ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 52
Author(s):  
Jerwin Jay E. Taping ◽  
Junie B. Billones ◽  
Voltaire G. Organo
Keyword(s):  
Density Functional Theory ◽  
Proton Transfer ◽  
Density Functional ◽  
Experimental Studies ◽  
Density Functional Theory Calculations ◽  
Catalytic Performance ◽  
Stoichiometric Ratio ◽  
Functional Theory ◽  
Pendant Arm ◽  
Spin Singlet

Nickel(II) complexes of mono-functionalized pyridine-tetraazamacrocycles (PyMACs) are a new class of catalysts that possess promising activity similar to biological peroxidases. Experimental studies with ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), substrate) and H2O2 (oxidant) proposed that hydrogen-bonding and proton-transfer reactions facilitated by their pendant arm were responsible for their catalytic activity. In this work, density functional theory calculations were performed to unravel the influence of pendant arm functionalization on the catalytic performance of Ni(II)–PyMACs. Generated frontier orbitals suggested that Ni(II)–PyMACs activate H2O2 by satisfying two requirements: (1) the deprotonation of H2O2 to form the highly nucleophilic HOO−, and (2) the generation of low-spin, singlet state Ni(II)–PyMACs to allow the binding of HOO−. COSMO solvation-based energies revealed that the O–O Ni(II)–hydroperoxo bond, regardless of pendant arm type, ruptures favorably via heterolysis to produce high-spin (S = 1) [(L)Ni3+–O·]2+ and HO−. Aqueous solvation was found crucial in the stabilization of charged species, thereby favoring the heterolytic process over homolytic. The redox reaction of [(L)Ni3+–O·]2+ with ABTS obeyed a 1:2 stoichiometric ratio, followed by proton transfer to produce the final intermediate. The regeneration of Ni(II)–PyMACs at the final step involved the liberation of HO−, which was highly favorable when protons were readily available or when the pKa of the pendant arm was low.

Sign in / Sign up

Export Citation Format

Share Document