Participants of the Ohio Supercomputer Center Workshop on Theory and Applications of Density Functional Approaches to Chemistry

Labanowski, Jan K.; Andzelm, Jan

doi:10.1007/978-1-4612-3136-3_30

Cited by 183 publications

(213 citation statements)

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“…Further, an ab initio [36] and density functional calculations were performed for the molecules I-III in gas phase and for the molecules lifted from the active site of p300 using GAUSSIAN03 program [37]. In the gas phase calculations, the molecules (I-III) were optimized with 6-311G ⁄⁄ basis set using Hartree-Fock (HF) [38] and DFT (B3LYP) [39,40] methods, whereas for the molecules lifted from the active site a single point energy calculation was carried out using the DFT method (B3LYP/6-311G ⁄⁄ ). The topological properties of electron densities of both forms of inhibitors were determined from the Bader's theory [41] of atoms in molecules (AIM) using ext94b routine incorporated to AIMPAC [42] software.…”

Section: Computational Detailsmentioning

confidence: 99%

Molecular flexibility and the electrostatic moments of curcumin and its derivatives in the active site of p300: A theoretical charge density study

Devipriya

Kumaradhas

2013

Chemico-Biological Interactions

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Section: Computational Detailsmentioning

confidence: 99%

Molecular flexibility and the electrostatic moments of curcumin and its derivatives in the active site of p300: A theoretical charge density study

Devipriya

Kumaradhas

2013

Chemico-Biological Interactions

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“…14 This is often good enough for such properties as molecular geometries and vibrational frequencies. 15 In contrast, an accurate treatment of exchange effects would seem of critical importance when comparing energies of different spin states. According to a common textbook explanation of Hund's rule, 16 exchange effects favor highspin states by keeping parallel spin electrons separated, thereby minimizing electron repulsion.…”

Section: Density Functionals and The Pairing-energy Problemmentioning

confidence: 99%

Comparison of density functionals for energy and structural differences between the high- [5T2g:(t2g)4(eg)2] and low- [1A1g:(t2g)6(eg)] spin states of iron(II) coordination compounds. II. More functionals and the hexaminoferrous cation, [Fe(NH3)6]2+

Fouqueau

Casida

Daku

et al. 2005

The Journal of Chemical Physics

168

164

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Comparison of density functionals for energy and structural differences between the high- † 5 T 2g :"t 2g … The ability of different density functionals to describe the structural and energy differences between the high-͓ 5 T 2g :(t 2g ) 4 (e g ) 2 ͔ and low-͓ 1 A 1g :(t 2g ) 6 (e g ) 0 ͔ spin states of small octahedral ferrous compounds is studied. This work is an extension of our previous study of the hexaquoferrous cation, ͓Fe(H 2 O) 6 ͔ 2ϩ , ͓J. Chem. Phys. 120, 9473 ͑2004͔͒ to include a second compound-namely, the hexaminoferrous cation, ͓Fe(NH 3 ) 6 ͔ 2ϩ -and several additional functionals. In particular, the present study includes the highly parametrized generalized gradient approximations ͑GGAs͒ known as HCTH and the meta-GGA VSXC ͓which together we refer to as highly parametrized density functionals ͑HPDFs͔͒, now readily available in the GAUSSIAN03 program, as well as the hybrid functional PBE0. Since there are very few experimental results for these molecules with which to compare, comparison is made with best estimates obtained from second-order perturbation theory-corrected complete active space self-consistent field ͑CASPT2͒ calculations, with spectroscopy oriented configuration interaction ͑SORCI͒ calculations, and with ligand field theory ͑LFT͒ estimations. While CASPT2 and SORCI are among the most reliable ab initio methods available for this type of problem, LFT embodies many decades of empirical experience. These three methods are found to give coherent results and provide best estimates of the adiabatic low-spin-high-spin energy difference, ⌬E LH adia , of 12 000-13 000 cm Ϫ1 for ͓Fe(H 2 O) 6 ͔ 2ϩ and 9 000-11 000 cm Ϫ1 for ͓Fe(NH 3 ) 6 ͔ 2ϩ . All functionals beyond the purely local approximation produce reasonably good geometries, so long as adequate basis sets are used. In contrast, the energy splitting, ⌬E LH adia , is much more sensitive to the choice of functional. The local density approximation severely over stabilizes the low-spin state with respect to the high-spin state. This ''density functional theory ͑DFT͒ spin pairing-energy problem'' persists, but is reduced, for traditional GGAs. In contrast the hybrid functional B3LYP underestimates ⌬E LH adia by a few thousands of wave numbers. The RPBE GGA of Hammer, Hansen, and Nørskov gives good results for ⌬E LH adia as do the HPDFs, especially the VSXC functional. Surprisingly the HCTH functionals actually over correct the DFT spin pairing-energy problem, destabilizing the low-spin state relative to the high-spin state. Best agreement is found for the hybrid functional PBE0. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1839854͔ I. INTRODUCTIONThe identification of the spin symmetry of the ground and low-lying excited states is important for the comprehension of chemical reactivity. However, many interesting cases occur, especially among transition metal coordination compounds, where the competition between the splitting of nearly degenerate orbitals with the electron pairing energy makes the prediction of relative spin-s...

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“…Calculations were done in the framework of the Density Functional Theory (DFT) 36 with the Gaussian03 package of programs. 37 The Becke's three parameter (B3) gradientcorrected exchange functional combined with the correlation Lee-Yang-Parr (LYP) functional was used.…”

Section: B Theoretical Calculationsmentioning

confidence: 99%

Diradicals acting through diamagnetic phenylene vinylene bridges: Raman spectroscopy as a probe to characterize spin delocalization

González

Nieto‐Ortega

González-Cano

et al. 2014

The Journal of Chemical Physics

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We present a complete Raman spectroscopic study in two structurally well-defined diradical species of different lengths incorporating oligo p-phenylene vinylene bridges between two polychlorinated triphenylmethyl radical units, a disposition that allows sizeable conjugation between the two radicals through and with the bridge. The spectroscopic data are interpreted and supported by quantum chemical calculations. We focus the attention on the Raman frequency changes, interpretable in terms of: (i) bridge length (conjugation length); (ii) bridge conformational structure; and (iii) electronic coupling between the terminal radical units with the bridge and through the bridge, which could delineate through-bond spin polarization, or spin delocalization. These items are addressed by using the "oligomer approach" in conjunction with pressure and temperature dependent Raman spectroscopic data. In summary, we have attempted to translate the well-known strategy to study the electron (charge) structure of π −conjugated molecules by Raman spectroscopy to the case of electron (spin) interactions via the spin delocalization mechanism. © 2014 AIP Publishing LLC.

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Participants of the Ohio Supercomputer Center Workshop on Theory and Applications of Density Functional Approaches to Chemistry

Cited by 183 publications

References 0 publications

Molecular flexibility and the electrostatic moments of curcumin and its derivatives in the active site of p300: A theoretical charge density study

Molecular flexibility and the electrostatic moments of curcumin and its derivatives in the active site of p300: A theoretical charge density study

Comparison of density functionals for energy and structural differences between the high- [5T2g:(t2g)4(eg)2] and low- [1A1g:(t2g)6(eg)] spin states of iron(II) coordination compounds. II. More functionals and the hexaminoferrous cation, [Fe(NH3)6]2+

Diradicals acting through diamagnetic phenylene vinylene bridges: Raman spectroscopy as a probe to characterize spin delocalization

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