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arxiv: 2311.05107 · v3 · submitted 2023-11-09 · ❄️ cond-mat.mes-hall

Impact of Exchange-Correlation Functionals on Predictions of Phonon Hydrodynamics: A Study of Fluorides, Chlorides, and Hydrides

Pith reviewed 2026-05-24 06:12 UTC · model grok-4.3

classification ❄️ cond-mat.mes-hall
keywords phonon hydrodynamicsexchange-correlation functionalslattice thermal conductivityBoltzmann transport equationdensity functional theoryfluorideshydrideschlorides
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The pith

Choice of exchange-correlation functional changes predicted thermal conductivity and the length-temperature window for phonon hydrodynamics in fluorides, chlorides, and hydrides.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper tests how three common density-functional approximations alter computed lattice thermal conductivities and the boundaries of the phonon-hydrodynamic regime in eight ionic crystals. It solves the linearized Boltzmann transport equation iteratively for each functional, applies Guyer's criterion to separate ballistic, hydrodynamic, and diffusive regimes, and finds that both conductivity values and the hydrodynamic window shift with the functional choice. The work confirms earlier reports for NaF and LiF while adding new predictions for the hydrides and chlorides, and it tracks isotope effects as well. A sympathetic reader would care because phonon hydrodynamics offers a route to unusually long phonon mean free paths; knowing which approximations move the observable window directly affects which materials experimentalists should target.

Core claim

The selection of an exchange-correlation functional impacts the prediction of thermal conductivity and the window for observation of phonon hydrodynamics. Using PBE, PBEsol, and LDA, the iterative Boltzmann-transport solution yields different conductivity magnitudes and different ranges of length scale and temperature that satisfy Guyer's hydrodynamic criterion; the same dependence appears when Meta-GGA and hybrid functionals are examined.

What carries the argument

Iterative solution of the linearized Boltzmann transport equation applied to phonon dispersions and scattering rates obtained from each exchange-correlation functional, combined with Guyer's criterion to delineate ballistic, hydrodynamic, and diffusive regimes.

If this is right

  • Phonon hydrodynamics is predicted to appear in NaH, LiH, KH, KF, NaCl, and KCl in addition to the previously reported NaF and LiF.
  • Isotope substitution alters both the conductivity magnitude and the size of the hydrodynamic window for each functional.
  • Meta-GGA and hybrid functionals produce further shifts in the same quantities.
  • The hydrodynamic regime boundaries depend explicitly on both length scale and temperature for every compound examined.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Because the hydrodynamic window moves with functional choice, experimental searches may need to test multiple DFT approximations to decide whether a given material truly lies inside the observable regime.
  • The sensitivity suggests that phonon hydrodynamics predictions in other ionic or polar materials could likewise depend on how electron correlation is approximated.
  • If higher-order scattering processes vary systematically with the same functionals, the present windows could be viewed as lower bounds on the true hydrodynamic region.

Load-bearing premise

The iterative solution of the linearized Boltzmann equation with the chosen functionals is assumed to capture the dominant scattering without higher-order or anharmonic contributions that would move the hydrodynamic boundaries.

What would settle it

An experiment that measures both the lattice thermal conductivity and a signature of the hydrodynamic regime (for example, second-sound propagation length or nonlocal heat transport) in NaH or KF at fixed temperature and varies the sample size across the predicted windows; mismatch between measured boundaries and the functional-dependent predictions would falsify the claim.

read the original abstract

We employ density functional theory calculations to examine the effect of various exchangecorrelation (XC) functionals, including the Perdew Burke Ernzerhof generalized gradient approximation (PBE), the modified Perdew Burke Ernzerhof generalized gradient approximation (PBEsol), and the local density approximation (LDA), on the electrical, mechanical, and thermal properties of sodium fluoride (NaF), lithium fluoride (LiF), potassium fluoride (KF), sodium chloride (NaCl), potassium chloride (KCl), lithium hydride (LiH), sodium hydride (NaH), and potassium hydride (KH). The lattice thermal conductivity is computed based on an iterative solution of the Boltzmann transport equation (BTE). Based on Guyer's criterion and direct solutions to the linearized BTE, we determine the ballistic, phonon hydrodynamics, and diffusive regimes as a function of length scale and temperature. In addition to confirming previous predictions of phonon hydrodynamics in NaF and LiF, we report novel predictions of phonon hydrodynamics in NaH, LiH, KH, KF, NaCl, and KCl. The impact of isotopes on the calculated lattice thermal conductivity and phonon hydrodynamics windows is also reported. The impact of Meta-GGA and hybrid functionals is also discussed. We find that the selection of a functional impacts the prediction of thermal conductivity and the window for observation of phonon hydrodynamics.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The paper employs DFT calculations with PBE, PBEsol, and LDA exchange-correlation functionals to compute electrical, mechanical, and thermal properties of NaF, LiF, KF, NaCl, KCl, LiH, NaH, and KH. Lattice thermal conductivity is obtained from iterative solutions of the linearized Boltzmann transport equation (BTE). Phonon transport regimes (ballistic, hydrodynamic, diffusive) are identified as functions of length scale and temperature using Guyer's criterion together with direct BTE solutions. The work confirms prior hydrodynamic predictions in NaF and LiF, reports novel predictions for the remaining compounds, examines isotope effects, briefly discusses Meta-GGA and hybrid functionals, and concludes that XC functional choice affects both thermal conductivity values and the hydrodynamic windows.

Significance. If the quantitative results hold after validation, the demonstration that XC functional selection shifts the predicted windows for phonon hydrodynamics would be useful for computational screening of candidate materials. The novel regime predictions for several hydrides and chlorides could help prioritize experiments. The study does not include machine-checked proofs or parameter-free derivations, but the systematic comparison across multiple functionals and compounds provides a concrete, falsifiable set of predictions.

major comments (3)
  1. [Abstract] Abstract: The claim that XC functional choice impacts the phonon hydrodynamics windows rests on the iterative linearized BTE plus Guyer's criterion being sufficient to delineate the regimes. No explicit quantification or bounds are given for four-phonon scattering contributions or higher-order anharmonic effects across the temperature and length-scale range, which directly affects whether the reported functional-induced shifts in the windows are robust.
  2. [Methods/Results] Methods/Results: No convergence data, error bars, or sensitivity tests are described for k-point sampling, supercell sizes used in force-constant calculations, or BTE iteration tolerance. These omissions make it impossible to assess whether the differences in thermal conductivity and regime boundaries between PBE, PBEsol, and LDA exceed numerical uncertainty.
  3. [Results] Results: The manuscript reports no direct comparison of the computed lattice thermal conductivities to experimental measurements for any of the eight compounds. Without such benchmarks it is unclear which functional yields the most reliable windows and therefore whether the functional-impact conclusion has predictive value.
minor comments (2)
  1. [Abstract] Abstract: The statement that Meta-GGA and hybrid functionals are discussed is not accompanied by any quantitative findings or comparisons in the provided text; a brief summary of those results should be added.
  2. Notation: Ensure that symbols for thermal conductivity, mean free path, and Guyer's criterion are defined consistently the first time they appear and that any tables reporting regime boundaries include the precise temperature and length values used.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We appreciate the referee's detailed review and suggestions for improving the manuscript. Below we provide point-by-point responses to the major comments.

read point-by-point responses
  1. Referee: [Abstract] Abstract: The claim that XC functional choice impacts the phonon hydrodynamics windows rests on the iterative linearized BTE plus Guyer's criterion being sufficient to delineate the regimes. No explicit quantification or bounds are given for four-phonon scattering contributions or higher-order anharmonic effects across the temperature and length-scale range, which directly affects whether the reported functional-induced shifts in the windows are robust.

    Authors: We agree that higher-order anharmonic effects, such as four-phonon scattering, can influence phonon lifetimes and thus the thermal conductivity and hydrodynamic windows, particularly at elevated temperatures. Our study employs the standard three-phonon BTE framework consistently across all functionals to isolate the effect of the XC functional. The relative differences in predicted windows due to functional choice are therefore meaningful within this approximation. We will revise the manuscript to explicitly discuss this limitation and note that a full assessment of four-phonon contributions would require additional calculations beyond the current scope. revision: partial

  2. Referee: [Methods/Results] Methods/Results: No convergence data, error bars, or sensitivity tests are described for k-point sampling, supercell sizes used in force-constant calculations, or BTE iteration tolerance. These omissions make it impossible to assess whether the differences in thermal conductivity and regime boundaries between PBE, PBEsol, and LDA exceed numerical uncertainty.

    Authors: We thank the referee for pointing this out. In the revised version, we will include convergence tests for k-point sampling, supercell sizes for force constants, and BTE iteration parameters. We will also provide error estimates or sensitivity analysis to demonstrate that the observed differences between functionals are larger than numerical uncertainties. revision: yes

  3. Referee: [Results] Results: The manuscript reports no direct comparison of the computed lattice thermal conductivities to experimental measurements for any of the eight compounds. Without such benchmarks it is unclear which functional yields the most reliable windows and therefore whether the functional-impact conclusion has predictive value.

    Authors: We acknowledge the value of experimental benchmarks. However, reliable experimental data for lattice thermal conductivity, especially for the hydrides (LiH, NaH, KH) and some fluorides/chlorides at the relevant temperatures, are scarce or unavailable in the literature. For compounds where data exist (e.g., LiF, NaCl), we will add comparisons in the revised manuscript. This will help contextualize which functional may be more reliable, while noting the limitations for the full set of materials. revision: yes

Circularity Check

0 steps flagged

No circularity; standard DFT+BTE pipeline with external methods

full rationale

The derivation applies standard DFT (PBE/PBEsol/LDA) to obtain force constants, followed by iterative solution of the linearized BTE for lattice thermal conductivity and application of Guyer's criterion to delineate ballistic/hydrodynamic/diffusive windows. No parameters are fitted to the reported windows or conductivities, no self-citation is invoked as a uniqueness theorem or load-bearing premise, and no ansatz or renaming reduces the outputs to the inputs by construction. The functional-impact comparison is a direct numerical evaluation against external benchmarks.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

Based solely on the abstract, the work relies on standard DFT and BTE machinery without introducing new fitted parameters or postulated entities; the only implicit assumptions are the usual domain assumptions of these methods.

axioms (1)
  • domain assumption Standard assumptions of density functional theory and the linearized Boltzmann transport equation are sufficient to identify phonon hydrodynamics regimes
    Invoked by the use of DFT with PBE/PBEsol/LDA and iterative BTE solution to classify ballistic/hydrodynamic/diffusive regimes.

pith-pipeline@v0.9.0 · 5791 in / 1355 out tokens · 23641 ms · 2026-05-24T06:12:21.583897+00:00 · methodology

discussion (0)

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Reference graph

Works this paper leans on

127 extracted references · 127 canonical work pages

  1. [1]

    R. A. Guyer and J. A. Krumhansl, Thermal Conductivity, Second Sound, and Phonon Hydrodynamic Phenomena in Nonmetallic Crystals, Phys. Rev. 148, 778 (1966)

  2. [2]

    H. E. Jackson, C. T. Walker, and T. F. McNelly, Second Sound in NaF, Phys. Rev. Lett. 25, 26 (1970)

  3. [3]

    van Mourik, M

    T. van Mourik, M. Bühl, and M.-P. Gaigeot, Density Functional Theory across Chemistry, Physics and Biology, Philos. Trans. R. Soc. A Math. Phys. Eng. Sci. 372, 20120488 (2014)

  4. [4]

    J. P. Perdew, K. Burke, and M. Ernzerhof, Generalized Gradient Approximation Made Simple, Phys. Rev. Lett. 77, 3865 (1996)

  5. [5]

    Chen and J

    Z. Chen and J. Yang, The B3LYP Hybrid Density Functional Study on Solids, Front. Phys. China 1, 339 (2006)

  6. [6]

    J. P. Perdew, A. Ruzsinszky, G. I. Csonka, O. A. Vydrov, G. E. Scuseria, L. A. Constantin, X. Zhou, and K. Burke, Restoring the Density-Gradient Expansion for Exchange in Solids and Surfaces, Phys. Rev. Lett. 100, 136406 (2008)

  7. [7]

    Zhang, A

    G.-X. Zhang, A. M. Reilly, A. Tkatchenko, and M. Scheffler, Performance of Various Density- Functional Approximations for Cohesive Properties of 64 Bulk Solids, New J. Phys. 20, 63020 (2018)

  8. [8]

    Persson and S

    C. Persson and S. Mirbt, Improved Electronic Structure and Optical Properties of Sp-Hybridized Semiconductors Using LDA+U SIC, Brazilian J. Phys. 36, 286 (2006)

  9. [9]

    Ishii, S

    S. Ishii, S. Iwata, and K. Ohno, All-Electron GW Calculations of Silicon, Diamond, and Silicon Carbide, Mater. Trans. 51, 2150 (2010)

  10. [10]

    C.-X. Zhao, Y. Huang, J.-Q. Wang, C.-Y. Niu, and Y. Jia, Prediction of a New Direct-Gap Silicon Phase: T36 Silicon, Phys. Lett. A 383, 125903 (2019)

  11. [11]

    Lindsay, D

    L. Lindsay, D. A. Broido, and T. L. Reinecke, First-Principles Determination of Ultrahigh Thermal Conductivity of Boron Arsenide: A Competitor for Diamond?, Phys. Rev. Lett. 111, 25901 (2013)

  12. [12]

    H. L. Parks, H.-Y. Kim, V. Viswanathan, and A. J. H. McGaughey, Uncertainty Quantification in First-Principles Predictions of Phonon Properties and Lattice Thermal Conductivity, Phys. Rev. Mater. 4, 83805 (2020)

  13. [13]

    Mortazavi, E

    B. Mortazavi, E. V. Podryabinkin, I. S. Novikov, T. Rabczuk, X. Zhuang, and A. V. Shapeev, Accelerating First-Principles Estimation of Thermal Conductivity by Machine-Learning Interatomic Potentials: A MTP/ShengBTE Solution, Comput. Phys. Commun. 258, 107583 29 (2021)

  14. [14]

    Jain and A

    A. Jain and A. J. H. McGaughey, Effect of Exchange–correlation on First-Principles-Driven Lattice Thermal Conductivity Predictions of Crystalline Silicon, Comput. Mater. Sci. 110, 115 (2015)

  15. [15]

    Ghosh, A

    K. Ghosh, A. Kusiak, and J.-L. Battaglia, Phonon Hydrodynamics in Crystalline GeTe at Low Temperature, Phys. Rev. B 102, 94311 (2020)

  16. [16]

    Ghosh, A

    K. Ghosh, A. Kusiak, and J.-L. Battaglia, Phonon Hydrodynamics in Crystalline Materials, J. Phys. Condens. Matter 34, 323001 (2022)

  17. [17]

    C. C. Ackerman and W. C. Overton, Second Sound in Solid Helium-3, Phys. Rev. Lett. 22, 764 (1969)

  18. [18]

    T. F. McNelly, S. J. Rogers, D. J. Channin, R. J. Rollefson, W. M. Goubau, G. E. Schmidt, J. A. Krumhansl, and R. O. Pohl, Heat Pulses in NaF: Onset of Second Sound, Phys. Rev. Lett. 24, 100 (1970)

  19. [19]

    Narayanamurti and R

    V. Narayanamurti and R. C. Dynes, Observation of Second Sound in Bismuth, Phys. Rev. Lett. 28, 1461 (1972)

  20. [20]

    Huberman, R

    S. Huberman, R. A. Duncan, K. Chen, B. Song, V. Chiloyan, Z. Ding, A. A. Maznev, G. Chen, and K. A. Nelson, Observation of Second Sound in Graphite at Temperatures above 100 K, Science (80-. ). 364, 375 (2019)

  21. [21]

    Z. Ding, K. Chen, B. Song, J. Shin, A. A. Maznev, K. A. Nelson, and G. Chen, Observation of Second Sound in Graphite over 200 K, Nat. Commun. 13, 285 (2022)

  22. [22]

    Cepellotti, G

    A. Cepellotti, G. Fugallo, L. Paulatto, M. Lazzeri, F. Mauri, and N. Marzari, Phonon Hydrodynamics in Two-Dimensional Materials, Nat. Commun. 6, 6400 (2015)

  23. [23]

    P. D. Pathak, J. M. Trivedi, and N. G. Vasavada, Thermal Expansion of NaF, KBr and RbBr and Temperature Variation of the Frequency Spectrum of NaF, Acta Crystallogr. Sect. A 29, 477 (1973)

  24. [24]

    Liang, W.-Q

    T. Liang, W.-Q. Chen, C.-E. Hu, X.-R. Chen, and Q.-F. Chen, Lattice Dynamics and Thermal Conductivity of Lithium Fluoride via First-Principles Calculations, Solid State Commun. 272, 28 (2018)

  25. [25]

    M. Born, K. Huang, and M. Lax, Dynamical Theory of Crystal Lattices, Am. J. Phys. 23, 474 (1955)

  26. [26]

    Tran and P

    F. Tran and P. Blaha, Accurate Band Gaps of Semiconductors and Insulators with a Semilocal Exchange-Correlation Potential, Phys. Rev. Lett. 102, 226401 (2009)

  27. [27]

    J. A. Camargo-Martínez and R. Baquero, Performance of the Modified Becke-Johnson Potential 30 for Semiconductors, Phys. Rev. B 86, 195106 (2012)

  28. [28]

    I. S. Messaoudi, A. Zaoui, and M. Ferhat, Band-Gap and Phonon Distribution in Alkali Halides, Phys. Status Solidi 252, 490 (2015)

  29. [29]

    Wang, Q.-K

    H.-Y. Wang, Q.-K. Hu, C.-Y. Li, Y.-C. Wang, and G.-F. Mi, Phase Transition, Elastic, and Thermodynamic Properties of NaF under High Pressure, Phase Transitions 85, 409 (2012)

  30. [30]

    Härtel, J

    S. Härtel, J. Vogt, and H. Weiss, Relaxation and Thermal Vibrations at the NaF(100) Surface, Surf. Sci. 604, 1996 (2010)

  31. [31]

    Prencipe, A

    M. Prencipe, A. Zupan, R. Dovesi, E. Aprà, and V. R. Saunders, Ab Initio Study of the Structural Properties of LiF, NaF, KF, LiCl, NaCl, and KCl, Phys. Rev. B 51, 3391 (1995)

  32. [32]

    Solovyeva and O

    A. Solovyeva and O. A. von Lilienfeld, Alchemical Screening of Ionic Crystals, Phys. Chem. Chem. Phys. 18, 31078 (2016)

  33. [33]

    CRC Handbook of Chemistry and Physics (CRC Press, 2014)

  34. [34]

    R. P. Lowndes and D. H. Martin, Dielectric Dispersion and the Structures of Ionic Lattices, Proc. R. Soc. London. Ser. A. Math. Phys. Sci. 308, 473 (1969)

  35. [35]

    Shukla, Ab Initio Hartree-Fock Born Effective Charges of LiH, LiF, LiCl, NaF, and NaCl, Phys

    A. Shukla, Ab Initio Hartree-Fock Born Effective Charges of LiH, LiF, LiCl, NaF, and NaCl, Phys. Rev. B 61, 13277 (2000)

  36. [36]

    Raunio, L

    G. Raunio, L. Almqvist, and R. Stedman, Phonon Dispersion Relations in NaCl, Phys. Rev. 178, 1496 (1969)

  37. [37]

    F. C. Brown, C. Gähwiller, H. Fujita, A. B. Kunz, W. Scheifley, and N. Carrera, Extreme- Ultraviolet Spectra of Ionic Crystals, Phys. Rev. B 2, 2126 (1970)

  38. [38]

    W. J. L. Buyers, Lattice Dynamics of Sodium Fluoride, Phys. Rev. 153, 923 (1967)

  39. [39]

    J. T. Lewis, A. Lehoczky, and C. V. Briscoe, Elastic Constants of the Alkali Halides at 4.2°K, Phys. Rev. 161, 877 (1967)

  40. [40]

    Haussühl, Z

    S. Haussühl, Z. Phys. 159, 223, (1960)

  41. [41]

    R. A. Miller and C. S. Smith, Pressure Derivatives of the Elastic Constants of LiF and NaF, J. Phys. Chem. Solids 25, 1279 (1964)

  42. [42]

    Otero-de-la-Roza and V

    A. Otero-de-la-Roza and V. Luaña, Gibbs2: A New Version of the Quasi-Harmonic Model Code. I. Robust Treatment of the Static Data, Comput. Phys. Commun. 182, 1708 (2011)

  43. [43]

    Spangenberg and S

    K. Spangenberg and S. Haussühl, Die Elastischen Konstanten Der Alkalihalogenide Vom Steinsalz-Typus, Zeitschrift Für Krist. 109, 422 (1957)

  44. [44]

    M. J. L. Sangster and R. M. Atwood, Interionic Potentials for Alkali Halides. II. Completely Crystal Independent Specification of Born-Mayer Potentials, J. Phys. C Solid State Phys. 11, 31 1541 (1978)

  45. [46]

    V Petrov, N

    A. V Petrov, N. S. Tsypkina, and Y. A. Logachev, Temperature Dependence of the Thermal Conductivity of Alkali Metal Halides at Elevated Temperatures, Fiz. Tverd. Tela 16, 65−70, (1974)

  46. [47]

    C. T. Walker, Thermal Conductivity of Some Alkali Halides Containing F Centers, Phys. Rev. 132, 1963 (1963)

  47. [48]

    A. E. Gheribi, M. Salanne, and P. Chartrand, Formulation of Temperature-Dependent Thermal Conductivity of NaF, β-Na3AlF6, Na5Al3F14, and Molten Na3AlF6 Supported by Equilibrium Molecular Dynamics and Density Functional Theory, J. Phys. Chem. C 120, 22873 (2016)

  48. [49]

    Touloukian and E

    Y.S. Touloukian and E. H. Buyco, Thermophysical Properties of Matter, Vol. Vol.5 (1970)

  49. [50]

    C. M. Kachhava and S. C. Saxena, Semiempirical Formulas for Thermal Expansion and Grüneisen Constants of Ionic Crystals, J. Appl. Phys. 39, 2973 (1968)

  50. [51]

    Ekinci and J

    Y. Ekinci and J. . Toennies, Thermal Expansion of the LiF(001) Surface, Surf. Sci. 563, 127 (2004)

  51. [52]

    Dolling, H

    G. Dolling, H. G. Smith, R. M. Nicklow, P. R. Vijayaraghavan, and M. K. Wilkinson, Lattice Dynamics of Lithium Fluoride, Phys. Rev. 168, 970 (1968)

  52. [53]

    D. M. Roessler and W. C. Walker, Electronic Spectrum of Crystalline Lithium Fluoride, J. Phys. Chem. Solids 28, 1507 (1967)

  53. [54]

    Piacentini, D

    M. Piacentini, D. W. Lynch, and C. G. Olson, Thermoreflectance of LiF between 12 and 30 eV, Phys. Rev. B 13, 5530 (1976)

  54. [55]

    F. J. Himpsel, L. J. Terminello, D. A. Lapiano-Smith, E. A. Eklund, and J. J. Barton, Band Dispersion of Localized Valence States in LiF(100), Phys. Rev. Lett. 68, 3611 (1992)

  55. [56]

    Lindsay, Isotope Scattering and Phonon Thermal Conductivity in Light Atom Compounds: LiH and LiF, Phys

    L. Lindsay, Isotope Scattering and Phonon Thermal Conductivity in Light Atom Compounds: LiH and LiF, Phys. Rev. B 94, 174304 (2016)

  56. [57]

    H. J. Hou, H. Guan, S. R. Zhang, L. H. Xie, and L. Wang, Structural, Phonon and Thermodynamic Properties of the Rocksalt Structure LiF from First Principles, Mater. Sci. Forum 850, 348 (2016)

  57. [58]

    W. G. Wyckoff, Crystal Structures, Wiley Vol. 1, (1968)

  58. [59]

    Bernardini and V

    F. Bernardini and V. Fiorentini, Electronic Dielectric Constants of Insulators Calculated by the Polarization Method, Phys. Rev. B 58, 15292 (1998). 32

  59. [60]

    M. Guo, X. Zhang, H. Gu, and N. Wang, Ab Initio Calculations of Electronic and Optical Properties in O-Doped LiF Crystal, Open Phys. 6, (2008)

  60. [61]

    E. L. Shirley, L. J. Terminello, J. E. Klepeis, and F. J. Himpsel, Detailed Theoretical Photoelectron Angular Distributions for LiF(100), Phys. Rev. B 53, 10296 (1996)

  61. [62]

    A. J. Cohen and R. G. Gordon, Theory of the Lattice Energy, Equilibrium Structure, Elastic Constants, and Pressure-Induced Phase Transitions in Alkali-Halide Crystals, Phys. Rev. B 12, 3228 (1975)

  62. [64]

    B. K. Singh, M. K. Roy, V. J. Menon, and K. C. Sood, Effects of Dispersion, Correction Term, and Isotopes on the Thermal Conductivity of LiF Crystal, Phys. Rev. B 67, 14302 (2003)

  63. [65]

    P. D. Pathak and N. G. Vasavada, Thermal Expansion of LiF by X-Ray Diffraction and the Temperature Variation of Its Frequency Spectrum, Acta Crystallogr. Sect. A 28, 30 (1972)

  64. [66]

    Wang, Single Crystal Elastic Constants and Calculated Aggregate Properties Handbook, Second Edition (1971)

    G.Simmons and H. Wang, Single Crystal Elastic Constants and Calculated Aggregate Properties Handbook, Second Edition (1971)

  65. [67]

    A. E. Gheribi and P. Chartrand, Application of the CALPHAD Method to Predict the Thermal Conductivity in Dielectric and Semiconductor Crystals, Calphad 39, 70 (2012)

  66. [68]

    J. L. Verble, J. L. Warren, and J. L. Yarnell, Lattice Dynamics of Lithium Hydride, Phys. Rev. 168, 980 (1968)

  67. [69]

    F. E. Pretzel, G. N. Rupert, C. L. Mader, E. K. Storms, G. V. Gritton, and C. C. Rushing, Properties of Lithium Hydride I. Single Crystals, J. Phys. Chem. Solids 16, 10 (1960)

  68. [70]

    M. H. Brodsky and E. Burstein, Infrared Lattice Vibrations of Single Crystal Lithium Hydride and Some of Its Isotopic Derivations, J. Phys. Chem. Solids 28, 1655 (1967)

  69. [71]

    Lucovsky, R

    G. Lucovsky, R. M. Martin, and E. Burstein, Localized Effective Charges in Diatomic Crystals, Phys. Rev. B 4, 1367 (1971)

  70. [72]

    D. K. Blat, N. E. Zein, and V. I. Zinenko, Calculations of Phonon Frequencies and Dielectric Constants of Alkali Hydrides via the Density Functional Method, J. Phys. Condens. Matter 3, 5515 (1991)

  71. [73]

    R. H. Lyddane, R. G. Sachs, and E. Teller, On the Polar Vibrations of Alkali Halides, Phys. Rev. 59, 673 (1941)

  72. [74]

    Laplaze, Étude Expérimentale de LiH, LiD ; Spectres de Réflexion Infrarouge et Spectres de Diffusion Raman Du Second Ordre, J

    D. Laplaze, Étude Expérimentale de LiH, LiD ; Spectres de Réflexion Infrarouge et Spectres de Diffusion Raman Du Second Ordre, J. Phys. 37, 1051 (1976)

  73. [75]

    M. J. van Setten, V. A. Popa, G. A. de Wijs, and G. Brocks, Electronic Structure and Optical 33 Properties of Lightweight Metal Hydrides, Phys. Rev. B 75, 35204 (2007)

  74. [76]

    X. Yang, Y. Zhao, Z. Dai, M. Zulfiqar, J. Zhu, and J. Ni, Thermal Expansion Induced Reduction of Lattice Thermal Conductivity in Light Crystals, Phys. Lett. A 381, 3514 (2017)

  75. [77]

    C. E. Messer, A SURVEY REPORT ON LITHIUM HYDRIDE, 1960

  76. [78]

    J. L. Anderson, J. Nasise, K. Phllipson, and F. E. Pretzel (deceased), Isotopic Effects on the Thermal Expansion of Lithium Hydride, J. Phys. Chem. Solids 31, 613 (1970)

  77. [79]

    G. Roma, C. M. Bertoni, and S. Baroni, The Phonon Spectra of LiH and LiD from Density- Functional Perturbation Theory, Solid State Commun. 98, 203 (1996)

  78. [80]

    Kondo and K

    Y. Kondo and K. Asaumi, Effect of Pressure on the Direct Energy Gap of LiH, J. Phys. Soc. Japan 57, 367 (1988)

  79. [81]

    V. G. Plekhanov, Wannier-Mott Excitons in Isotope-Disordered Crystals, Reports Prog. Phys. 61, 1045 (1998)

  80. [82]

    X. Yang, T. Feng, J. Li, and X. Ruan, Stronger Role of Four-Phonon Scattering than Three- Phonon Scattering in Thermal Conductivity of III-V Semiconductors at Room Temperature, Phys. Rev. B 100, 245203 (2019)

Showing first 80 references.