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Methods to efficiently determine the relative stability of polymorphs of organic crystals are highly desired in crystal structure predictions (CSPs). Current methodologies include use of static lattice phonons, quasi-harmonic approximation…

Materials Science · Physics 2020-06-08 Nathan S. Abraham , Michael R. Shirts

Motivated by the negative thermal expansion observed for silicon between 20 K and 120 K, we present first an ab initio study of the volume dependence of interatomic force constants, phonon frequencies of TA(X) and TA(L) modes, and of the…

mtrl-th · Physics 2009-10-28 G. -M. Rignanese , J. -P. Michenaud , X. Gonze

To compute and analyze vibrationally resolved electronic spectra at zero temperature, we have recently implemented the on-the-fly ab initio extended thawed Gaussian approximation [A. Patoz et al., J. Phys. Chem. Lett. 9, 2367 (2018)], which…

Chemical Physics · Physics 2024-09-26 Tomislav Begušić , Jiří Vaníček

Heat sources whose characteristic dimension $R$ is comparable to phonon mean free paths display thermal resistances that exceed conventional diffusive predictions. This has direct implications to (opto)electronics thermal management and…

Mesoscale and Nanoscale Physics · Physics 2018-01-17 Bjorn Vermeersch , Natalio Mingo

We coupled first principles calculations and the quasiharmonic approximation combined with experiments (X-Ray diffraction and dilatometry measurements) to determine the thermal properties of NiTiSn (half-Heusler) and Ni2TiSn (Heusler)…

Materials Science · Physics 2015-04-08 P. Hermet , R. M. Ayral , E. Theron , P. G. Yot , F. Salles , M. Tillard , P. Jund

Computing the temperature and stress dependence of the full elastic constant tensor from first-principles in non-cubic materials remains a challenging problem. Here we circumvent the aforementioned challenge via the generalized…

Materials Science · Physics 2024-03-01 Mark A. Mathis , Chris A. Marianetti

The thermal properties of materials are critically important to various technologies and are increasingly the target of materials design efforts. However, it is only relatively recent advances in first-principles computational techniques…

Materials Science · Physics 2021-12-08 Ethan T. Ritz , Nicole A. Benedek

Metal-organic frameworks often display large positive or negative thermal expansion coefficients. MOF-74, a material envisioned for many applications does not display such a behavior. For this system, temperature-dependent x-ray diffraction…

Materials Science · Physics 2022-01-19 Tomas Kamencek , Benedikt Schrode , Roland Resel , Raffaele Ricco , Egbert Zojer

The thermal expansion of the wide band gap semiconductor MgSiN$_{2}$ has been determined using density functional calculations in combination with the quasi-harmonic approximation. We find that the thermal expansion is rather small in good…

Materials Science · Physics 2018-03-14 Mikael Råsander , Michelle A. Moram

Machine-learning interatomic potentials are widely used as computationally efficient surrogates for density functional theory in atomistic simulations, enabling large-scale, long-time modeling of materials systems. We investigate how…

Materials Science · Physics 2026-04-13 Jonas Grandel , Philipp Benner , Janine George

The PHASEGO package extracts the Helmholtz free energy from the phonon density of states obtained by the first-principles calculations. With the help of equation of states fitting, it reduces the Gibbs free energy as a function of…

Materials Science · Physics 2015-06-23 Zhong-Li Liu

The free energy and other thermodynamic properties of hexagonal-close-packed iron are calculated by direct {\em ab initio} methods over a wide range of pressures and temperatures relevant to the Earth's core. The {\em ab initio}…

Condensed Matter · Physics 2007-05-23 D. Alfe` , G. D. Price , M. J. Gillan

The calculation of pair correlations and density profiles of quasiholes are routine steps in the study of proposed fractional quantum Hall states. Nevertheless, the field has not adopted a standard way to present the results of such…

Strongly Correlated Electrons · Physics 2023-06-07 Jørgen Fulsebakke , Mikael Fremling , Niall Moran , J. K. Slingerland

We report a comprehensive temperature dependent Raman measurements on three different phases of monolayer WS2 from 4K to 330K in a wide spectral range. Our studies revels the anomalous nature of the first as well as the higher order…

Materials Science · Physics 2020-01-08 Deepu Kumar , Birender Singh , Pawan Kumar , Viswanath Balakrishnan , Pradeep Kumar

We approximate boson thermodynamic integrals as polynomials in two variables chosen to give the correct limiting expansions and to smoothly interpolate into other regimes. With 10 free parameters, an accuracy of better than 0.009\% is…

Nuclear Theory · Physics 2009-10-30 S. M. Johns , P. J. Ellis , J. M. Lattimer

The thermal properties of silver are calculated within the quasi-harmonic approximation, by using phonon dispersions from density-functional perturbation theory, and the pseudopotential plane-wave method. The resulting free energy provides…

Materials Science · Physics 2009-10-31 Jianjun Xie , Stefano de Gironcoli , Stefano Baroni , Matthias Scheffler

The thermal properties of bulk copper are investigated by performing ab initio DFT and DFPT calculations and using the quasiharmonic approximation for the free energy. Using both the LDA and the GGA for the exchange-correlation potential,…

Materials Science · Physics 2009-11-07 Shobhana Narasimhan , Stefano de Gironcoli

The anharmonic phonon properties of SnSe in the Pnma phase were investigated with a combination of experiments and first-principles simulations. Using inelastic neutron scattering (INS) and nuclear resonant inelastic X-ray scattering…

Knowledge of lattice anharmonicity is essential to elucidate distinctive thermal properties in crystalline solids. Yet, accurate \textit{ab initio} investigations of lattice anharmonicity encounter difficulties owing to the cumbersome…

Materials Science · Physics 2022-04-13 Zhen Zhang , Dong-Bo Zhang , Tao Sun , Renata M. Wentzcovitch

The occurrence of thermal transport phenomena is widespread, exerting a pivotal influence on the functionality of diverse electronic and thermo-electric energy-conversion devices. The traditional first-principles theory governing the…

Materials Science · Physics 2026-05-20 Soham Mandal , Manish Jain , Prabal K. Maiti