Infrared intensities and Raman-scattering activities within density-functional theory

Porezag, D.; Pederson, Mark R.

doi:10.1103/physrevb.54.7830

Cited by 642 publications

(536 citation statements)

References 36 publications

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“…1,2 Reliable calculation of Raman frequencies and intensities of mechanically stable structures can be obtained using density functional perturbation theory (DFPT) 3,4 based on ab initio lattice dynamics (LD). 5,6 However these methods do not include high-temperature effects and fail for dynamically stabilized structures with imaginary phonon frequencies.…”

Section: Introductionmentioning

confidence: 99%

Identification of high-pressure phases III and IV in hydrogen: Simulating Raman spectra using molecular dynamics

2013

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We present a technique for extracting Raman intensities from ab initio molecular dynamics (MD) simulations at high temperature. The method is applied to the highly anharmonic case of dense hydrogen up to 500 K for pressures ranging from 180 to 300 GPa. On heating or pressurizing we find first-order phase transitions under the experimental conditions of the phase III-IV boundary. At even higher pressures, close to 350 GPa, we find a second phase transformation to the previously proposed Cmca-4. Our method enables, for the first time, a direct comparison of Raman vibrons between theory and experiment at finite temperature. This turns out to provide excellent discrimination between subtly different structures found in MD. We find candidate structures whose Raman spectra are in good agreement with experiment. The new phase obtained in hightemperature simulations adopts a dynamic, simple hexagonal structure with three layer types: freely rotating hydrogen molecules, static hexagonal trimers, and rotating hexagonal trimers. We show that previously calculated structures for phase IV are inconsistent with experiment, and their appearance in simulation is due to finite-size effects.

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Section: Introductionmentioning

confidence: 99%

Identification of high-pressure phases III and IV in hydrogen: Simulating Raman spectra using molecular dynamics

2013

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“…The vibrational results have followed the methods of Ref. [31]. All geometries discussed in this work are found to have positive-definite hessian matrices.…”

Section: Theoretical and Computational Detailsmentioning

confidence: 99%

“…Calculation of the S = 1 Raman spectra, within PBE-GGA or PW92-LDA was complicated by the fact that there are two energetically similar S = 1 states. Application of electric fields seemed to mix these states, which made it difficult to reliably determine the derivatives of the polarizability tensors [31] needed to calculate the Raman spectra. Since the inclusion of the self-interaction correction significantly opens the HOMO/LUMO gap, it is reasonable to expect that this instability will not be present in a fully self-consistent SIC method.…”

Section: Zero-point Vibrational Contributions and Vibrational Signaturesmentioning

confidence: 99%

The Role of Self-Interaction Corrections, Vibrations, and Spin-Orbit in Determining the Ground Spin State in a Simple Heme

et al. 2017

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Without self-interaction corrections or the use of hybrid functionals, approximations to the density-functional theory (DFT) often favor intermediate spin systems over high-spin systems. In this paper, we apply the recently proposed Fermi-Löwdin-orbital self-interaction corrected density functional formalism to a simple tetra-coordinated Fe(II)-porphyrin molecule and show that the energetic orderings of the S = 1 and S = 2 spin states are changed qualitatively relative to the results of Generalized Gradient Approximation (developed by Perdew, Burke, and Ernzerhof, PBE-GGA) and Local Density Approximation (developed by Perdew and Wang, PW92-LDA). Because the energetics, associated with changes in total spin, are small, we have also calculated the second-order spin-orbit energies and the zero-point vibrational energies to determine whether such corrections could be important in metal-substituted porphins. Our results find that the size of the spin-orbit and vibrational corrections to the energy orderings are small compared to the changes due to the self-interaction correction. Spin dependencies in the Infrared (IR)/Raman spectra and the zero-field splittings are provided as a possible means for identifying the spin in porphyrins containing Fe(II).

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“…Excellent agreement with experiment was found for these three materials. As noted earlier, LDA-based methods for the prediction of infrared and Raman activities in small molecules have been investigated in [124] and [125], and for C 60 , LDA-based calculations of the IR and Raman intensities have been published by Bertsch et al [113] and by Giannozzi and Baroni [47]. The latter authors' predicted relative intensities for the 10 first-order Raman modes in C 60 are shown in Fig.…”

Section: Absolute Raman Cross Sectionsmentioning

confidence: 97%

“…This is equivalent to computing the third derivative of the many-electron ground state energy, twice with respect to an external static electric field and once with respect to an atomic displacement. LDA-based calculation of this sort have been made for small molecules [124,125]. Giannozzi and Baroni [47] have used Density Functional Perturbation Theory to carry out such calculations for the polarizability derivatives of C 60 .…”

Section: Relative Intensities For Off-resonance Scatteringmentioning

confidence: 99%

Vibrational spectroscopy of C60

Menéndez¹,

Page²

Topics in Applied Physics

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The fullerene era was started in 1985 with the discovery of the stable C 60 cluster and its interpretation as a cage structure with the familiar shape of a soccer ball [1]. An explosive growth in fullerene research was triggered in 1990 by the development of a method to produce fullerenes in bulk quantities [2]. Subsequently, the structural, electronic, and vibrational properties of many fullerenes have been studied in detail. The importance and potential of this new class of materials is exemplified by the discovery of intermediatetemperature superconductivity in doped C 60 [3]. Carbon nanotubes, a novel form of carbon which combines the properties of graphite and fullerenes, were discovered in 1991 [4]. Because of their intriguing properties and potential for applications, nanotubes are currently the subject of very intense research. Polymerization of C 60 molecules, particularly by photoexcitation [5] but by several other techniques as well, also results in a variety of interesting new structures, which contain both 4-coordinated and 3-coordinated carbon atoms [6]. The burgeoning field of fullerene research has been reviewed by several authors [7][8][9][10][11][12], most notably by Dresselhaus et al. [11] in an extensive monograph that appeared in 1996.In spite of the rapidly increasing interest in new forms of fullerenes, icosahedral C 60 , the "most beautiful molecule" [13], remains the focus of vigorous research as the prototype fullerene system. The present chapter concerns the vibrational structure of C 60 and the efforts to unravel its details using spectroscopic techniques. This remains a work in progress, but we hope to show that a look at the existing body of experimental and theoretical research from the broader perspective of an extended article provides a deeper understanding of the vibrational properties of C 60 .

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Infrared intensities and Raman-scattering activities within density-functional theory

Cited by 642 publications

References 36 publications

Identification of high-pressure phases III and IV in hydrogen: Simulating Raman spectra using molecular dynamics

Identification of high-pressure phases III and IV in hydrogen: Simulating Raman spectra using molecular dynamics

The Role of Self-Interaction Corrections, Vibrations, and Spin-Orbit in Determining the Ground Spin State in a Simple Heme

Vibrational spectroscopy of C60

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