<i>Ab initio</i>phonon dispersion in crystalline naphthalene using van der Waals density functionals

Brown-Altvater, Florian; Rangel, Tonatiuh; Neaton, Jeffrey B.

doi:10.1103/physrevb.93.195206

Cited by 49 publications

(79 citation statements)

References 85 publications

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“…The GW correction is important as it stretches the valence band, thus lowering the hole effective mass and changing the relative alignment of the valence band valleys. The quality of our phonon dispersions is comparable with that of recent accurate phonon calculations in naphthalene [52]. To further validate our phonon calculations, we also compute the phonon dispersions of perdeuterated naphthalene, for which experimental data are available (see Fig.…”

Section: Methodssupporting

confidence: 72%

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Charge transport in organic molecular semiconductors from first principles: The bandlike hole mobility in a naphthalene crystal

et al. 2018

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Predicting charge transport in organic molecular crystals is notoriously challenging. Carrier mobility calculations in organic semiconductors are dominated by quantum chemistry methods based on charge hopping, which are laborious and only moderately accurate. We compute from first principles the electron-phonon scattering and the phonon-limited hole mobility of naphthalene crystal in the framework of ab initio band theory. Our calculations combine GW electronic bandstructures, ab initio electron-phonon scattering, and the Boltzmann transport equation. The calculated hole mobility is in very good agreement with experiment between 100-300 K, and we can predict its temperature dependence with high accuracy. We show that scattering between intermolecular phonons and holes regulates the mobility, though intramolecular phonons possess the strongest coupling with holes. We revisit the common belief that only rigid molecular motions affect carrier dynamics in organic molecular crystals. Our paper provides a quantitative and rigorous framework to compute charge transport in organic crystals and is a first step toward reconciling band theory and carrier hopping computational methods.

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Section: Methodssupporting

confidence: 72%

“…Calculated dispersion of the 12 intermolecular phonon modes for perdeuterated naphthalene, with lattice constants taken from Refs. [64], [52]. The markers are the experimental data at 6 K from Ref.…”

Section: Acknowledgmentsmentioning

confidence: 99%

Charge transport in organic molecular semiconductors from first principles: The bandlike hole mobility in a naphthalene crystal

et al. 2018

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“…This is done by comparing the simulated DFT phonon band structure of deuterated naphthalene to the available experimental data 18 . As part of this comparison, different a posteriori van-der-Waals (vdW) corrections within DFT are tested, extending a previous study by Brown-Altvater et al 30 . DFTB-and FF-calculated phonon bands are, subsequently, compared to the results of the aforementioned DFT reference results.…”

Section: Introductionmentioning

confidence: 95%

Evaluating Computational Shortcuts in Supercell-Based Phonon Calculations of Molecular Crystals: The Instructive Case of Naphthalene

Kamencek

Wieser

Kojima

et al. 2020

J. Chem. Theory Comput.

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Phonons crucially impact a variety of properties of organic semiconductor materials. For instance, charge-and heat transport depend on low-frequency phonons, while for other properties, such as the free energy, especially high-frequency phonons count. For all these quantities one needs to know the entire phonon band structure, whose simulation becomes exceedingly expensive for more complex systems when using methods like dispersion-corrected density functional theory (DFT). Therefore, in the present contribution we evaluate the performance of more approximate methodologies, including density functional tight binding (DFTB) and a pool of force fields (FF) of varying complexity and sophistication. Beyond merely comparing phonon band structures, we also critically evaluate to what extent derived quantities, like temperature-dependent heat capacities, mean squared thermal displacements and temperaturedependent free energies are impacted by shortcomings in the description of the phonon bands. As a benchmark system, we choose (deuterated) naphthalene, as the only organic semiconductor material for which to date experimental phonon band structures are available in the literature.Overall, the best performance amongst the approximate methodologies is observed for a systemspecifically parametrized second-generation force field. Interestingly, in the low-frequency regime also force fields with a rather simplistic model for the bonding interactions (like the General Amber Force Field) perform rather well. As far as the tested DFTB parametrization is concerned, we obtain a significant underestimation of the unit cell volume resulting in a pronounced overestimation of the phonon energies in the low frequency region. This cannot be mended by relying on the DFT-calculated unit cell, since with this unit cell the DFTB phonon frequencies significantly underestimate the experiments.3

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“…Recent works have reported advances in the treatment of vdW interactions. Brown-Altvater, Rangel, and Neaton [38] showed that including vdW interactions enabled the accurate prediction of structural parameters and phonon frequencies of crystalline naphthalene. Kleis et al [39] accurately predicted structural, cohesive, and elastic properties for crystalline polyethylene by including vdW interactions via the vdW density functional [35].…”

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confidence: 99%

Lattice Thermal Conductivity of Polyethylene Molecular Crystals from First-Principles Including Nuclear Quantum Effects

2017

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Molecular crystals such as polyethylene are of intense interest as flexible thermal conductors, yet their intrinsic upper limits of thermal conductivity remain unknown. Here, we report a study of the vibrational properties and lattice thermal conductivity of a polyethylene molecular crystal using an ab initio approach that rigorously incorporates nuclear quantum motion and finite temperature effects. We obtain a thermal conductivity along the chain direction of around 160 W m −1 K −1 at room temperature, providing a firm upper bound for the thermal conductivity of this molecular crystal. Furthermore, we show that the inclusion of quantum nuclear effects significantly impacts the thermal conductivity by altering the phase space for three-phonon scattering. Our computational approach paves the way for ab initio studies and computational material discovery of molecular solids free of any adjustable parameters. DOI: 10.1103/PhysRevLett.119.185901 Polymers have long been of interest for their potential as flexible thermal conductors in applications such as flexible electronics [1][2][3][4]. In bulk form, essentially all polymers are thermal insulators, with a thermal conductivity of less than 1 W m −1 K −1 , due to the random orientation of the molecular chains [5]. However, samples with highly aligned molecular chains may exhibit thermal conductivities as much as 2 orders of magnitude larger. Early work by Choy, Chen, and Luk [6] demonstrated that increasing the crystallinity in polymers drives an increase in thermal conductivity along the direction of the covalently bonded molecular chains. In low-density polyethylene, for instance, they reported increased thermal conductivity along the chain direction from 0.4 to 1.5 W m −1 K −1 when the polymers are stretched by a factor of 5. Other experiments on mechanically stretched bulk polyethylene [7,8] report thermal conductivities as high as ∼42 W m −1 K −1 along the stretching direction due to crystalline alignment of the chains.More recently, Shen et al.[9] reported a high thermal conductivity of around 100 W m −1 K −1 in high-quality ultradrawn polyethylene nanofibers. Wang et al.[10] used an optical method to study heat transport along polymer fibers, reporting thermal conductivity on the order of tens of W m −1 K −1 for polymers such as crystalline polyethylene and poly (p-phenylene benzobisoxazole). Singh et al.[11] reported amorphous aligned polythiophene fibers with a thermal conductivity of around 4 W m −1 K −1 , a factor of 20 increase over that of the unaligned fibers.Despite these experimental advances, the theoretical treatment of heat transport in molecular crystals remains less developed. Molecular dynamics has been used in many studies to examine heat transport in polymers such as stretched polyethylene [12] and polydimethylsiloxane [13]. However, the semiempirical potentials used in these studies restrict their predictive power, especially for the polymers for which experimental data are scarce or unavailable.Additionally, as with covalent crystals,...

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Ab initiophonon dispersion in crystalline naphthalene using van der Waals density functionals

Cited by 49 publications

References 85 publications

Charge transport in organic molecular semiconductors from first principles: The bandlike hole mobility in a naphthalene crystal

Charge transport in organic molecular semiconductors from first principles: The bandlike hole mobility in a naphthalene crystal

Evaluating Computational Shortcuts in Supercell-Based Phonon Calculations of Molecular Crystals: The Instructive Case of Naphthalene

Lattice Thermal Conductivity of Polyethylene Molecular Crystals from First-Principles Including Nuclear Quantum Effects

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