First-principles calculations of hyperfine parameters with the Gaussian and augmented-plane-wave method: Application to radicals embedded in a crystalline environment

Declerck, Reinout; Pauwels, Ewald; Speybroeck, Véronique Van; Waroquier, Michel

doi:10.1103/physrevb.74.245103

Cited by 48 publications

(92 citation statements)

References 46 publications

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“…[16][17][18] In this regard, the so-called projector-augmented-wave ͑PAW͒ method proposed by Blöchl 19 has shown to yield highly accurate frozen-core wave functions in the core regions and hence is considered as a reliable method for calculating HFPs of systems with s-like SOMO, e.g., hydrogen defects in Si. 15 Another important aspect of HFPs computed through PP formalism has only very recently received attention: the effect of core spin polarization was considered by Yazyev et al 20 and Declerck et al 21 The former 20 is similar in spirit to the current work, but approaches the treatment of the core spin polarization differently. In the so-called core spin-polarization correction ͑CSPC͒ method, 20 a reconstruction of the AE wave functions and the frozen-valence spin-density approximation are used to solve the Kohn-Sham equations for core states only.…”

Section: Introductionmentioning

confidence: 74%

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Pseudopotential hyperfine calculations through perturbative core-level polarization

Bahramy

Sluiter

2007

Phys. Rev. B

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Within density functional theory, an efficient and accurate method for calculating the hyperfine parameters in the context of pseudopotential formalism is proposed. The spin density at and in the vicinity of the nucleus is evaluated in two steps. First, a transformation due to Blöchl ͓Phys. Rev. B 50, 17953 ͑1994͔͒ is applied to reconstruct the frozen-core all-electron wave functions in the core regions. Second, the contributions of core orbitals to the charge density at the nucleus are evaluated through first-order perturbation theory in which the perturbing potential is defined as a functional of charge and spin densities. The current pseudopotential based method makes it possible to predict hyperfine parameters of complex molecular assemblies and crystal defects with an accuracy as good as current all-electron method with less computational cost.

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Section: Introductionmentioning

confidence: 74%

“…Moreover, within this approach, still one cannot calculate the anisotropic HFPs. In the latter, 21 a hybrid method is proposed in which the nuclei of interest are described with an all-electron treatment and a PP approximation is used for the remaining atoms. Nontheless, this method appears sensitive to the choice of basis set.…”

Section: Introductionmentioning

confidence: 99%

Pseudopotential hyperfine calculations through perturbative core-level polarization

Bahramy

Sluiter

2007

Phys. Rev. B

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“…In energy minimizations and NEB runs, the Gaussian and plane waves (GPW) dual basis set method 42 was used, employing a TZVP triple-ζ Gaussian basis set 43 and plane waves (400 Ry density cut-off) with GTH pseudopotentials. 44,45 For the calculation of EPR properties (g-and hyperfine coupling tensors), we relied on recent implementations in the CP2K code, 46,47 employing the all-electron Gaussian and augmented plane wave (GAPW) method. 48 The density cut-off for the auxiliary plane wave basis set was 200 Ry and the all-electron TZVP basis 49 was used.…”

Section: Computational Detailsmentioning

confidence: 99%

Solved? The reductive radiation chemistry of alanine

Pauwels

Cooman

Waroquier

et al. 2014

Phys. Chem. Chem. Phys.

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The structural changes throughout the entire reductive radiation-induced pathway of L-α-alanine are solved on an atomistic level with the aid of periodic DFT and nudged elastic band (NEB) simulations. This yields unprecedented information on the conformational changes taking place, including the protonation state of the carboxyl group in the "unstable" and "stable" alanine radicals and the internal transformation converting these two radical variants at temperatures above 220 K. The structures of all stable radicals were verified by calculating EPR properties and comparing those with experimental data. The variation of the energy throughout the full radiochemical process provides crucial insight in the reason why these structural changes and rearrangements occur. Starting from electron capture, the excess electron quickly localizes on the carbon of a carboxyl group, which pyramidalizes and receives a proton from the amino group of a neighboring alanine molecule, forming a first stable radical species (up to 150 K). In the temperature interval 150-220 K, this radical deaminates and deprotonates at the carboxyl group, the detached amino group undergoes inversion and its methyl group sustains an internal rotation. This yields the so-called "unstable alanine radical". Above 220 K, triggered by the attachment of an additional proton on the detached amino group, the radical then undergoes an internal rotation in the reverse direction, giving rise to the "stable alanine radical", which is the final stage in the reductive radiation-induced decay of alanine.2

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“…A further major improvement in the calculations came from the implementation of HF [98] and g tensor calculations [99,100] in periodic codes (CP2K) using Gaussian and augmented plane wave basis sets. This allowed to perform the SH parameter calculations directly on the periodically optimized structure.…”

Section: Dft Calculations : Evolving Methodologymentioning

confidence: 99%

Radiation Chemistry of Solid-State Carbohydrates Using EMR

Vrielinck

Cooman

Callens

et al. 2014

Applications of EPR in Radiation Research

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We review our research of the past decade towards identification of radiation-induced radicals in solid state sugars and sugar phosphates. Detailed models of the radical structures are obtained by combining EPR and ENDOR experiments with DFT calculations of g and proton HF tensors, with agreement in their anisotropy serving as most important criterion. Symmetry-related and Schonland ambiguities, which may hamper such identification, are reviewed. Thermally induced transformations of initial radiation damage into more stable radicals can also be monitored in the EPR (and ENDOR) experiments and in principle provide information on stable radical formation mechanisms. Thermal annealing experiments reveal, however, that radical recombination and/or diamagnetic radiation damage is also quite important. Analysis strategies are illustrated with research on sucrose. Results on dipotassium glucose-1-phosphate and trehalose dihydrate, fructose and sorbose are also briefly discussed. Our study demonstrates that radiation damage is strongly regio-selective and that certain general principles govern the stable radical formation.

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First-principles calculations of hyperfine parameters with the Gaussian and augmented-plane-wave method: Application to radicals embedded in a crystalline environment

Cited by 48 publications

References 46 publications

Pseudopotential hyperfine calculations through perturbative core-level polarization

Pseudopotential hyperfine calculations through perturbative core-level polarization

Solved? The reductive radiation chemistry of alanine

Radiation Chemistry of Solid-State Carbohydrates Using EMR

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