722 citations · 3.1k across the 23 of their papers we have counts for
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Hybrid ab initio method for examining thermal properties in magnetic materials
Matthew Heine, Olle Hellman, David Broido
A hybrid ab initio theoretical approach for examining thermal properties in magnetic systems of unknown entropy is presented. Commonly used theoretical approaches interrogate therm…
Phonon-phonon interactions in the polarizarion dependence of Raman scattering
Nimrod Benshalom, Maor Asher, Rémy Jouclas +6
We have found that the polarization dependence of Raman scattering in organic crystals at finite temperatures can only be described by a fourth-rank formalism. This generalization…
The dielectric response of rock-salt crystals at finite temperatures from first principles
Nimrod Benshalom, Guy Reuveni, Roman Korobko +2
We combine ab initio simulations and Raman scattering measurements to demonstrate explicit anharmonic effects in the temperature dependent dielectric response of a NaCl single crys…
Unraveling heat transport and dissipation in suspended MoSe crystals from bulk to monolayer
D. Saleta Reig, S. Varghese, R. Farris +14
Understanding thermal transport in layered transition metal dichalcogenide (TMD) crystals is crucial for a myriad of applications exploiting these materials. Despite significant ef…
Direct Observation of Chiral Phonons by Inelastic X-ray Scattering
Qingan Cai, Olle Hellman, Bin Wei +5
Phonon chirality has attracted intensive attention since it breaks the traditional cognition that phonons are linear propagating bosons. This new quasiparticle property has been ex…
The origin of the lattice thermal conductivity enhancement at the ferroelectric phase transition in GeTe
Đorđe Dangić, Olle Hellman, Stephen Fahy +1
The proximity to structural phase transitions in IV-VI thermoelectric materials is one of the main reasons for their large phonon anharmonicity and intrinsically low lattice therma…
Anharmonicity and Ultra-Low Thermal Conductivity in Lead-Free Halide Double Perovskites
Johan Klarbring, Olle Hellman, Igor A. Abrikosov +1
The lead-free halide double perovskite class of materials offers a promising venue for resolving issues related to toxicity of Pb and long-term stability of the lead-containing hal…
Impact of anharmonicity on sound wave velocities at extreme conditions
Olle Hellman, S. I. Simak
Theoretical calculations of sound-wave velocities of materials at extreme conditions are of great importance to various fields, in particular geophysics. For example, the seismic d…
Thermoelectric transport trends in group 4 half-Heusler alloys
Kristian Berland, Nina Shulumba, Olle Hellman +2
The thermoelectric properties of 54 different group 4 half-Heusler (HH) alloys have been studied from first principles. Electronic transport was studied with density functional the…
Vibrational Effects in X-ray Absorption Spectra of 2D Layered Materials
Weine Olovsson, Teruyasu Mizoguchi, Martin Magnuson +4
With the examples of the C -edge in graphite and the B -edge in hexagonal BN, we demonstrate the impact of vibrational coupling and lattice distortions on the X-ray absorptio…
Order-disorder transition in the prototypical antiferroelectric PbZrO
Bin Xu, Olle Hellman, L. Bellaiche
The prototypical antiferroelectric PbZrO has several unsettled questions, such as the nature of the antiferroelectric transition, possible intermediate phase and the microscopi…
Electron-Phonon Scattering in the Presence of Soft Modes and Electron Mobility in SrTiO Perovskite from First Principles
Jin-Jian Zhou, Olle Hellman, Marco Bernardi
Structural phase transitions and soft phonon modes pose a longstanding challenge to computing electron-phonon (e-ph) interactions in strongly anharmonic crystals. Here we develop a…
A nuclear quantum effect with pure anharmonicity and the anomalous thermal expansion of silicon
D. S. Kim, O. Hellman, J. Herriman +7
Despite the widespread use of silicon in modern technology, its peculiar thermal expansion is not well-understood. Adapting harmonic phonons to the specific volume at temperature,…
Intrinsic localized mode and low thermal conductivity of PbSe
Nina Shulumba, Olle Hellman, Austin J. Minnich
Lead chalcogenides such as PbS, PbSe, and PbTe are of interest for their exceptional thermoelectric properties and strongly anharmonic lattice dynamics. Although PbTe has received…
Efficient and accurate determination of lattice-vacancy diffusion coefficients via non equilibrium ab initio molecular dynamics
Davide G. Sangiovanni, Olle Hellman, Björn Alling +1
We revisit the color-diffusion algorithm [P. C. Aeberhard et al., Phys. Rev. Lett. 108, 095901 (2012)] in nonequilibrium ab initio molecular dynamics (NE-AIMD), and propose a simpl…
Anharmonicity changes the solid solubility of an alloy at high temperatures
Nina Shulumba, Olle Hellman, Zamaan Raza +5
We have developed a method to accurately and efficiently determine the vibrational free energy as a function of temperature and volume for substitutional alloys from first principl…
Phonon quarticity induced by changes in phonon-tracked hybridization during lattice expansion and its stabilization of rutile TiO
Tian Lan, C. W. Li, O. Hellman +5
Although the rutile structure of TiO is stable at high temperatures, the conventional quasiharmonic approximation predicts that several acoustic phonons decrease anomalously to…
Vibrational free energy and phase stability of paramagnetic and antiferromagnetic CrN from ab-initio molecular dynamics
Nina Shulumba, Björn Alling, Olle Hellman +4
We present a theoretical first-principles method to calculate the free energy of a magnetic system in its high-temperature paramagnetic phase, including vibrational, electronic, an…
Thermal Anharmonic Effects in PbTe from First Principles
A. H. Romero, E. K. U. Gross, M. J. Verstraete +1
We investigate the harmonic and anharmonic contributions to the phonon spectrum of lead telluride, and perform a complete characterization of how the anharmonic effects dominate th…
Phonon self-energy and origin of anomalous neutron scattering spectra in SnTe and PbTe thermoelectrics
C. W. Li, O. Hellman, J. Ma +8
The anharmonic lattice dynamics of rock-salt thermoelectric compounds SnTe and PbTe are investigated with inelastic neutron scattering (INS) and first-principles calculations. The…
Temperature dependent effective third order interatomic force constants from first principles
Olle Hellman, Igor A. Abrikosov
The temperature dependent effective potential (TDEP) method is generalized beyond pair interactions. The second and third order force constants are determined consistently from ab…
Lattice dynamics of anharmonic solids from first principles
Olle Hellman, I. A. Abrikosov, S. I. Simak
An accurate and easily extendable method to deal with lattice dynamics of solids is offered. It is based on first-principles molecular dynamics simulations and provides a consisten…