Relative Energy Computations with Approximate Density Functional Theory — A Caveat!

ChemInform ◽  
2007 ◽  
Vol 38 (33) ◽  
Author(s):  
Peter R. Schreiner
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Relative Energy ◽  
Functional Theory

scholarly journals Assessing Density Functional Theory Approaches for Predicting the Structure and Relative Energy of Salicylideneaniline Molecular Switches in the Solid State

2017 ◽  
Vol 121 (12) ◽  
pp. 6898-6908 ◽  
Author(s):  
Jean Quertinmont ◽  
Andrea Carletta ◽  
Nikolay A. Tumanov ◽  
Tom Leyssens ◽  
Johan Wouters ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Solid State ◽  
Density Functional ◽  
Molecular Switches ◽  
Relative Energy ◽  
Functional Theory

Density functional theory study of bis(imino) N-heterocyclic carbene iron(II) complexes

2014 ◽  
Vol 92 (10) ◽  
pp. 925-931 ◽  
Author(s):  
Jameel Al Thagfi ◽  
Gino G. Lavoie
Keyword(s):  
Density Functional Theory ◽  
Electron Density ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Iron Complexes ◽  
Relative Energy ◽  
Iron Complex ◽  
Geometrical Parameters ◽  
Functional Theory ◽  
Imine Group

Density functional theory calculations at the B3LYP/DGDZVP and UB3LYP/TZVP levels were performed on 1,3-bis[1-(2,6-dimethylphenylimino)ethyl]imidazolium and on the corresponding imidazol-2-ylidene iron(II) dichloride complex, respectively. The resulting geometrical parameters of the optimized structures were in good agreement with previously reported X-ray structures. The ground state for the high-spin (quintet multiplicity) iron complex is 82.4 kJ/mol lower in energy compared to the low-spin (triplet) configuration, in agreement with magnetic susceptibility measurements. Further calculations were carried out on related benzimidazol-2-ylidene and pyrimidin-2-ylidene ligands and on the corresponding iron complexes to gain insight into their electronic properties and reactivities. The energy of the highest occupied and lowest unoccupied molecular orbitals of all three carbenes suggests that the pyrimidin-2-ylidene and the benzimidazol-2-ylidene are the best σ-donor and best π-acceptor, respectively. Using those results, the metal center in the pyrimidin-2-ylidene iron dichloride complex was predicted to bear the highest electron density. This was supported by the high relative energy of its highest occupied molecular orbital compared to that of the corresponding imidazole-2-ylidene and benzimidazol-2-ylidene iron complexes. The electrostatic potential maps of all three metal complexes furthermore indicated a marked decrease in electron density for the coordinated imine group, supporting a greater reactivity towards nucleophiles.

Ab Initio Theoretical Studies of Relative Stabilities and IR Spectrum of 5-Methylcytosine Tautomers

2003 ◽  
Vol 2003 (4) ◽  
pp. 195-199 ◽  
Author(s):  
Lida Ghassemzadeh ◽  
Majid Monajjemi ◽  
Karim Zare
Keyword(s):  
Density Functional Theory ◽  
Gas Phase ◽  
Density Functional ◽  
Relative Energy ◽  
Theoretical Studies ◽  
Functional Theory ◽  
Relative Stabilities ◽  
B3lyp Method ◽  
Wide Range ◽  
Good Agreement

The structure and relative energies of the tautomers of 5-methylcytosine in the gasphase and in different solvents are predicted using MP2 and density functional theory methods. The order of stability for these tautomers is C3>C1>C2>C4>C5>C6 calculated by MP2 and C1>C3>C2>C4>C5>C6 calculated by the B3LYP method. Relative energy calculations are performed in wide range of solvent dielectrics and in all solvents the oxo-amino C1 is predicted as the most stable tautomer. The infrared spectra of two dominant tautomers are calculated in the gas phase using HF and density functional theory. Good agreement between calculated (DFT) and experimental harmonic vibrational frequencies is found.

scholarly journals Termination Effects in Aluminosilicate and Aluminogermanate Imogolite Nanotubes: A Density Functional Theory Study

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1051
Author(s):  
Emiliano Poli ◽  
Joshua D. Elliott ◽  
Ziwei Chai ◽  
Gilberto Teobaldi
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Finite Size ◽  
Relative Energy ◽  
Finite Model ◽  
Functional Theory ◽  
Band Bending ◽  
Longitudinal Effects ◽  
Screening And Identification ◽  
Dft Simulations

We investigate termination effects in aluminosilicate (AlSi) and aluminogermanate (AlGe) imogolite nanotubes (NTs) by means of semi-local and range-corrected hybrid Density Functional Theory (DFT) simulations. Following screening and identification of the smallest finite model capable of accommodating full relaxation of the NT terminations around an otherwise geometrically and electrostatically unperturbed core region, we quantify and discuss the effects of physical truncation on the structure, relative energy, electrostatics and electronic properties of differently terminated, finite-size models of the NTs. In addition to composition-dependent changes in the valence (VB) and conduction band (CB) edges and resultant band gap (BG), the DFT simulations uncover longitudinal band bending and separation in the finite AlSi and AlGe models. Depending on the given termination of the NTs, such longitudinal effects manifest in conjunction with the radial band separation typical of fully periodic AlSi and AlGe NTs. The strong composition dependence of the longitudinal and radial band bending in AlSi and AlGe NTs suggests different mechanisms for the generation, relaxation and separation of photo-generated holes in AlSi and AlGe NTs, inviting further research in the untapped potential of imogolite compositional and structural flexibility for photo-catalytic applications.

Doping effects on the geometric and electronic structure of tin clusters

2019 ◽  
Vol 21 (44) ◽  
pp. 24478-24488 ◽  
Author(s):  
Martin Gleditzsch ◽  
Marc Jäger ◽  
Lukáš F. Pašteka ◽  
Armin Shayeghi ◽  
Rolf Schäfer
Keyword(s):  
Density Functional Theory ◽  
Electronic Structure ◽  
Density Functional ◽  
Beam Deflection ◽  
Functional Theory ◽  
Doping Effects ◽  
Depth Analysis ◽  
Trajectory Simulations

In depth analysis of doping effects on the geometric and electronic structure of tin clusters via electric beam deflection, numerical trajectory simulations and density functional theory.

What correlation effects are covered by density functional theory?

2000 ◽  
Vol 98 (20) ◽  
pp. 1639-1658 ◽  
Author(s):  
Yuan He, Jurgen Grafenstein, Elfi Kraka,
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Correlation Effects ◽  
Functional Theory
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