Center for Molecular Modeling - J. Jaeken

A new ab initio equation of state of hcp-Fe and its implication on the interior structure and mass-radius relations of rocky super-Earths

leen — Thu, 09 Dec 2021 13:59:56 +0000

K. Hakim, A. Rivoldini, T. Van Hoolst, S. Cottenier, J. Jaeken, T. Chust, G. Steinle-Neuman, G. Steinle-Neumann

Icarus

Volume 313, pages 61-78

2018

Abstract

More than a third of all exoplanets can be classified as super-Earths based on radius (1-2 R-circle plus)) and mass (

DOI

http://dx.doi.org/10.1016/j.icarus.2018.05.005

Private attachment

1-s2.0-S0019103517305602-main.pdf

Solving the Christoffel equation: phase and group velocities

jjaeken — Mon, 26 Sep 2016 17:05:37 +0000

J. Jaeken, S. Cottenier

Computer Physics Communications

207, 445–451

2016

Abstract

We provide christoffel, a Python tool for calculating direction-dependent phase velocities, polarization vectors, group velocities, power flow angles and enhancement factors based on the stiffness tensor of a solid. It is built in a modular way to allow for efficient and flexible calculations, and the freedom to select and combine results as desired. All derivatives are calculated analytically, which circumvents possible numerical sampling problems. GNUPlot scripts are provided for convenient visualization.

Open Access version available at UGent repository

DOI

http://dx.doi.org/10.1016/j.cpc.2016.06.014

Private attachment

1-s2.0-S0010465516301795-main.pdf

Quasi-1D physics in Metal-Organic Frameworks: MIL-47(V) from first principles

kurt — Thu, 03 Jul 2014 06:53:14 +0000

D.E.P. Vanpoucke, J. Jaeken, S. De Baerdemacker, K. Lejaeghere, V. Van Speybroeck

Beilstein Journal of Nanotechnology

5, 1738–1748

2014

Abstract

The geometric and electronic structure of the MIL-47(V) metal-organic framework (MOF) is investigated by using ab initio density functional theory (DFT) calculations. Special focus is placed on the relation between the spin configuration and the properties of the MOF. The ground state is found to be antiferromagnetic, with an equilibrium volume of 1554.70 Å³. The transition pressure of the pressure-induced large-pore-to-narrow-pore phase transition is calculated to be 82 MPa and 124 MPa for systems with ferromagnetic and antiferromagnetic chains, respectively. For a mixed system, the transition pressure is found to be a weighted average of the ferromagnetic and antiferromagnetic transition pressures. Mapping DFT energies onto a simple-spin Hamiltonian shows both the intra- and inter-chain coupling to be antiferromagnetic, with the latter coupling constant being two orders of magnitude smaller than the former, suggesting the MIL-47(V) to present quasi-1D behavior. The electronic structure of the different spin configurations is investigated and it shows that the band gap position varies strongly with the spin configuration. The valence and conduction bands show a clear V d-character. In addition, these bands are flat in directions orthogonal to VO₆ chains, while showing dispersion along the the direction of the VO6 chains, similar as for other quasi-1D materials

Open Access version available at UGent repository

DOI

http://dx.doi.org/10.3762/bjnano.5.184

Private attachment

14_Beilstein_5,1738_Vanpoucke.pdf

Ab initio based thermal property predictions at a low cost: An error analysis

kurt — Thu, 14 Nov 2013 09:13:30 +0000

K. Lejaeghere, J. Jaeken, V. Van Speybroeck, S. Cottenier

Physical Review B

89, 014304

2014

Abstract

Ab initio calculations often do not straightforwardly yield the thermal properties of a material yet. It requires considerable computational efforts, for example, to predict the volumetric thermal expansion coefficient αV or the melting temperature Tm from first principles. An alternative is to use semi-empirical approaches. They relate the experimental values to first-principles predictors via fits or approximative models. Before applying such methods, however, it is of paramount importance to be aware of the expected errors. We therefore quantify these errors at the DFT-PBE level for several semi-empirical approximations of αV and Tm , and compare them to the errors from fully ab initio methods, which are computationally more intensive. We base our conclusions on a benchmark set of 71 ground-state elemental crystals. For the thermal expansion coefficient, it appears that simple quasiharmonic theory, in combination with different approximations to the Gruneisen parameter, provides a similar overall accuracy as exhaustive first-principles phonon calculations. For the melting temperature, expensive ab initio molecular-dynamics simulations still outperform semi-empirical methods.

Open Access version available at UGent repository

DOI

http://dx.doi.org/10.1103/PhysRevB.89.014304

Private attachment

Lejaeghere_2014_PRB_semi-empirical-errors.pdf

Predicting sound in planetary inner cores using quantum physics

jjaeken — Mon, 22 Feb 2016 10:55:47 +0000

J. Jaeken, A. Rivoldini, T. Van Hoolst, V. Van Speybroeck, M. Waroquier, S. Cottenier

ISBN/ISSN:

Poster

Conference / event / venue

VSC user day

Antwerp, Belgium

Monday, 30 November, 2015

80th Annual Conference of the DPG and DPG Spring Meeting

wim — Fri, 22 Jan 2016 14:16:34 +0000

Regensburg, Germany

Sunday, 6 March, 2016 to Friday, 11 March, 2016

Participant(s)

J. Jaeken

Project ref.

FWO Mercurius (3G040211) B/11781/*

Conference reference

80th Annual Conference of the DPG and DPG Spring Meeting

Quasi-1D physics in breathing metal-organic frameworks

danny — Fri, 12 Jun 2015 11:46:51 +0000

D.E.P. Vanpoucke, J. Jaeken, S. De Baerdemacker, V. Van Speybroeck, K. Lejaeghere

ISBN/ISSN:

Poster

Conference / event / venue

DZA 2014 meeting

Ghent, Belgium

Tuesday, 7 October, 2014

New quasi-1D materials: DFT-study of breathing metal-organic frameworks

danny — Fri, 12 Jun 2015 11:44:17 +0000

D.E.P. Vanpoucke, J. Jaeken, S. De Baerdemacker, K. Lejaeghere, A. Ghysels, M. Waroquier, V. Van Speybroeck

ISBN/ISSN:

Poster

Conference / event / venue

IAP P7/05 Annual meeting 2014

Louvain-La-Neuve, Belgium

Friday, 19 September, 2014

Low dimensional physics in Metal-Organic Frameworks: a DFT study of breathing MIL-47

danny — Thu, 28 May 2015 08:44:33 +0000

D.E.P. Vanpoucke, J. Jaeken, S. De Baerdemacker, K. Lejaeghere, V. Van Speybroeck

ISBN/ISSN:

Poster

Conference / event / venue

Belgian Physical Society Meeting 2015

Liège, Belgium

Wednesday, 13 May, 2015

Abstract (private)

BPS_abstract_MOFsBeilstein.pdf

Copper diffusion in germanium from first principles : a first step towards high-throughput diffusivity studies in silicon and germanium

wim — Tue, 07 Apr 2015 07:38:06 +0000