Gibbs2: A new version of the quasiharmonic model code. II. Models for solid-state thermodynamics, features and implementation ☆ ☆☆
TL;DR: The Gibbs 2 code is presented, a Fortran90 reimplementation of the original Gibbs program for the calculation of pressure–temperature dependent thermodynamic properties of solids under the quasiharmonic approximation.
About: This article is published in Computer Physics Communications.The article was published on 2011-10-01. It has received 574 citations till now. The article focuses on the topics: Source code & Unix.
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TL;DR: The recently implemented exchange-hole dipole moment (XDM) model is compared with other approaches in the literature to find that XDM roughly doubles the accuracy of DFT-D2 and non-local functionals in computed lattice energies while, at the same time, predicting cell geometries within less than 2% of the experimental result on average.
Abstract: A benchmark for non-covalent interactions in solids (C21) based on the experimental sublimation enthalpies and geometries of 21 molecular crystals is presented. Thermal and zero-point effects are carefully accounted for and reference lattice energies and thermal pressures are provided, which allow dispersion-corrected density functionals to be assessed in a straightforward way. Other thermal corrections to the sublimation enthalpy (the 2RT term) are reexamined. We compare the recently implemented exchange-hole dipole moment (XDM) model with other approaches in the literature to find that XDM roughly doubles the accuracy of DFT-D2 and non-local functionals in computed lattice energies (4.8 kJ/mol mean absolute error) while, at the same time, predicting cell geometries within less than 2% of the experimental result on average. The XDM model of dispersion interactions is confirmed as a very promising approach in solid-state applications.
308 citations
01 Jan 1997
Abstract: Abstract In situ x-ray data on molar volumes of periclase and tungsten have been collected over the temperature range from 300 K to melting. We determine the temperature by combining the technique of spectroradiometry and electrical resistance wire heating. The thermal expansion (α) of periclase between 300 and 3100 K is given by α=2.6025 10−5+1.3535 10−8 T+6.5687 10−3 T−1−1.8281 T−2.For tungsten, we have (300 to 3600 K) α=7.862 10−6+6.392 10−9 T.The data at 298 K for periclase is: molar volume 11.246 (0.031) cm3, α=3.15 (0.07) 10−5 K−1, and for tungsten: molar volume 9.55 cm3, α=9.77 (10.08) 10−6 K−1.
163 citations
TL;DR: The covalent character of S-S bond is confirmed, and the favored cleavage of CuS at the [001] surface might be at the Cu-S Bond, explaining the conductivity anisotropy observed experimentally.
Abstract: Covellite (CuS) is an important mineral sulfide that can be used in many technological applications. It has a simple formula but a complex structure consisting of alternating layers of planar CuS3 triangles and CuS4 tetrahedrons with S–S bonds. Accurate first-principles calculations are performed for covellite structure (CuS), aiming to provide insights about its structural, mechanical and electronic properties and to unveil the nature of its chemical bonding. DFT and DFT+U methods have been used and showed to be sensitive to the correlation treatment (U value). Although it is not possible to extract a universal value of the U, this study indicates that U = 5 eV is an adequate value. The electronic structure analysis shows a significant metallic character due to p(S)–d(Cu) orbital interactions up to Fermi level. The projected density of states indicates that most of the contribution comes from the atomic orbitals in the [001] plane of the covellite, explaining the conductivity anisotropy observed experime...
98 citations
TL;DR: In this article, the effect of pressure and temperature on the Debye temperature, bulk modulus, heat capacity and thermal expansion coefficient of Ti3AlC2 and Ti3SiC2 has been investigated.
94 citations
TL;DR: In this paper, the phonon spectra of several 2H-MT2 structures using the density functional perturbation theory (DFPT) were analyzed and the symmetry properties of phonon modes were analyzed.
Abstract: We calculated the phonon spectra of several 2H-MT2 structures using the density functional perturbation theory (DFPT). The symmetry properties of phonon modes are analyzed. The mode-Gruneisen parameters and phonon velocities are calculated using phonon spectra. All the investigated structures show very large phase velocities (>10 000 m s−1) and small group velocities (<600 m s−1). The macroscopic Gruneisen parameter of the [001] direction is larger than that of the [010] direction for 2H-MT2 phases. The volumetric and linear thermal expansion coefficients are evaluated using the quasi-harmonic approximation (QHA) between 0 K and 1100 K. The negative thermal expansion coefficients are discovered in the 2H-WS2 structure. Our results show that the properties in the [001] direction are very different to the [010] direction, because of the significant difference in the chemical bonding in the two crystallographic directions for these layered materials.
89 citations
References
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Book•
11 Feb 1988TL;DR: In this paper, the gear predictor -corrector is used to calculate forces and torques in a non-equilibrium molecular dynamics simulation using Monte Carlo methods. But it is not suitable for the gear prediction problem.
Abstract: Introduction Statistical mechanics Molecular dynamics Monte Carlo methods Some tricks of the trade How to analyse the results Advanced simulation techniques Non-equilibrium molecular dynamics Brownian dynamics Quantum simulations Some applications Appendix A: Computers and computer simulation Appendix B: Reduced units Appendix C: Calculation of forces and torques Appendix D: Fourier transforms Appendix E: The gear predictor - corrector Appendix F: Programs on microfiche Appendix G: Random numbers References Index.
21,073 citations
"Gibbs2: A new version of the quasih..." refers background in this paper
...There are essentially two mainstream ways of incorporating temperature in a theoretical calculation: molecular dynamics simulations [5,6] and the quasiharmonic approximation (QHA) [7]....
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University of Udine1, National Research Council2, International School for Advanced Studies3, Massachusetts Institute of Technology4, University of Paris5, Princeton University6, University of Minnesota7, ParisTech8, University of Milan9, International Centre for Theoretical Physics10, University of Paderborn11, ETH Zurich12, École Polytechnique Fédérale de Lausanne13
TL;DR: QUANTUM ESPRESSO as discussed by the authors is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave).
Abstract: QUANTUM ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density-functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave). The acronym ESPRESSO stands for opEn Source Package for Research in Electronic Structure, Simulation, and Optimization. It is freely available to researchers around the world under the terms of the GNU General Public License. QUANTUM ESPRESSO builds upon newly-restructured electronic-structure codes that have been developed and tested by some of the original authors of novel electronic-structure algorithms and applied in the last twenty years by some of the leading materials modeling groups worldwide. Innovation and efficiency are still its main focus, with special attention paid to massively parallel architectures, and a great effort being devoted to user friendliness. QUANTUM ESPRESSO is evolving towards a distribution of independent and interoperable codes in the spirit of an open-source project, where researchers active in the field of electronic-structure calculations are encouraged to participate in the project by contributing their own codes or by implementing their own ideas into existing codes.
19,985 citations
TL;DR: Novel features are that the pseudopotential itself becomes charge-state dependent, the usual norm-conservation constraint does not apply, and a generalized eigenproblem is introduced.
Abstract: A new approach to the construction of first-principles pseudopotentials is described. The method allows transferability to be improved systematically while holding the cutoff radius fixed, even for large cutoff radii. Novel features are that the pseudopotential itself becomes charge-state dependent, the usual norm-conservation constraint does not apply, and a generalized eigenproblem is introduced. The potentials have a separable form well suited for plane-wave solid-state calculations, and show promise for application to first-row and transition-metal systems.
18,782 citations
TL;DR: Quantum ESPRESSO as discussed by the authors is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave).
Abstract: Quantum ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density-functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave). Quantum ESPRESSO stands for "opEn Source Package for Research in Electronic Structure, Simulation, and Optimization". It is freely available to researchers around the world under the terms of the GNU General Public License. Quantum ESPRESSO builds upon newly-restructured electronic-structure codes that have been developed and tested by some of the original authors of novel electronic-structure algorithms and applied in the last twenty years by some of the leading materials modeling groups worldwide. Innovation and efficiency are still its main focus, with special attention paid to massively-parallel architectures, and a great effort being devoted to user friendliness. Quantum ESPRESSO is evolving towards a distribution of independent and inter-operable codes in the spirit of an open-source project, where researchers active in the field of electronic-structure calculations are encouraged to participate in the project by contributing their own codes or by implementing their own ideas into existing codes.
13,052 citations
Book•
01 Jan 1954
TL;DR: Born and Huang's classic work on the dynamics of crystal lattices was published over thirty years ago, and it remains the definitive treatment of the subject as mentioned in this paper. But it is not the most complete work on crystal lattice dynamics.
Abstract: Although Born and Huang's classic work on the dynamics of crystal lattices was published over thirty years ago, the book remains the definitive treatment of the subject. It begins with a brief introduction to atomic forces, lattice vibrations and elasticity, and then breaks off into four sections. The first section deals with the general statistical mechanics of ideal lattices, leading to the electric polarizability and to the scattering of light. The second section deals with the properties of long lattice waves, the third with thermal properties, and the fourth with optical properties.
7,756 citations
"Gibbs2: A new version of the quasih..." refers background in this paper
...Even for a system as simple as MgO, γS differs from the experimental or from the reference QHA result by a non-negligible factor....
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...2 shows the Grüneisen ratio in the Slater approximation, calculated using the full QHA and the experimental result....
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...In increasing order of complexity and accuracy: Debye–Slater, Debye–Grüneisen, Debye–Einstein and the full QHA....
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...Even with its intrinsic limitations, the QHA has recently achieved a great deal of success in the prediction of equations of state and thermodynamic properties....
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...Using xopt, instead of x(p, T ), in the context of the QHA leads to what other authors have called the statically constrained QHA [16]....
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