Center for Molecular Modeling - D.M. Tomecka

Multi-aspect modelling and quantum effects in molecular nanomagnets

Daria — Fri, 16 Nov 2012 19:12:01 +0000

D.M. Tomecka

ACTA PHYSICAE SUPERFICIERUM

2009

Abstract

Note:
Published while none of the authors are employed at UGent

Open Access version available at UGent repository

DOI

http://dx.doi.org/

Multi-aspect modelling and quantum effects in molecular nanomagnets

Daria — Fri, 16 Nov 2012 19:03:01 +0000

G. Kamieniarz, M. Antkowiak, P. Sobczak, T. Slusarski, D.M. Tomecka, P. Kozlowski, A. Barasinski, A. Drzewinski, J. Klak, A. Bienko, J. Mrozinski, V. Bellini, F. Troiani, F. Manghi, M. Affronte, A. Olivieri, F. Tuna, G.A. Timco, R.E.P. Winpenny

ACTA PHYSICAE SUPERFICIERUM

2009

Abstract

Note:
Published while none of the authors are employed at UGent

Open Access version available at UGent repository

DOI

http://dx.doi.org/

Anisotropy, geometric structure and frustration effects in molecule-based nanomagnets

Daria — Fri, 16 Nov 2012 18:54:17 +0000

G. Kamieniarz, P. Kozlowski, M. Antkowiak, P. Sobczak, T. Slusarski, D.M. Tomecka, A. Barasinski, B. Brzostowski, A. Drzewinski, A. Bienko, J. Mrozinski

Acta Physica Polonica A

121, 5-6, 992-998

2011

Published while none of the authors were employed at the CMM

Abstract

In this paper we review our results of comprehensive study of molecular nanomagnets recently synthesized in the form of the chromium-based molecules and bimetallic copper-containing chains as well as we present some new findings. We focus on effects of anisotropy, geometry and frustration appearing in various thermodynamic properties of the nanoscale magnets which are described by Heisenberg-like spin models and simulated by accurate numerical methods. We show that bond-dependent exchange anisotropy is needed to model magnetic torque in the Cd-doped chromium ring. We argue that only in the limit of infinite rings (n -> infinity) frustration can be considered as the opposite to bipartiteness in the odd numbered (3

DOI

http://dx.doi.org/

Electronic structure and magnetic properties of a molecular octanuclear chromium-based ring

Daria — Fri, 16 Nov 2012 18:47:30 +0000

T. Slusarski, B. Brzostowski, D.M. Tomecka, G. Kamieniarz

JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY

11, 10

2011

Published while none of the authors were employed at the CMM

Abstract

A comprehensive study of electronic and magnetic properties of Cr(8)F(8)Piv(16) (HPiv = pivalic acid, trimethyl acetic acid) molecular ring is presented. The total, local and orbital projected density of states are calculated by the first principle density functional theory calculations using the package SIESTA. The original molecule has been approximated by replacing the pivallic groups by H atoms (hydrogen saturation). Electron density, deformation density, electrostatic potential and spin density maps are analyzed and compared with experiment for the first time. Magnetic properties are investigated in detail. Magnetic moments are calculated using two different approaches: the Mulliken one and integration of muffin-tin sphere with a given radius. Different magnetic configurations (ferromagnetic, antiferromagnetic and many more with randomly distributed spins up and down) are considered to extract exchange interaction parameter J and check the stability of its estimate.

DOI

http://dx.doi.org/10.1166/jnn.2011.4300

SBO In Silico Materials

wim — Tue, 23 Apr 2013 13:06:03 +0000

Project promotor

V. Van Speybroeck, M. Waroquier

Financierende instantie

SBO-IWT

Project data

01/01/2009 to 31/12/2012

Bedrag

€250 000,00

Project titel

In Silico Materials Design and experimental validation for novel optical coatings

Personeel

S. Cottenier, K. Rijpstra, D.M. Tomecka

Extra info

Partner CMM: V. Van Speybroeck - M. Waroquier
[J.Paul (Flamac), D.Lamoen (UA), B.Partoens (UA), X.Gonze (UCL)]
(*) bedrag: partim CMM

Project ref.

SBO In Silico Materials B/10784/*

17th ETSF Workshop on Electronic Excitations

wim — Thu, 17 Jan 2013 10:59:46 +0000

Coimbra, Portugal

Tuesday, 2 October, 2012 to Friday, 5 October, 2012

Participant(s)

S. Cottenier, D.M. Tomecka

Project ref.

SBO In Silico Materials B/10784/*

Conference reference

17th ETSF Workshop on Electronic Excitations

Ground state configurations and melting of two-dimensional non-uniformly charged classical clusters

Daria — Fri, 16 Nov 2012 19:35:55 +0000

D.M. Tomecka, G. Kamieniarz, B. Partoens, F.M. Peeters

Journal of Physics: Condensed Matter

21, 15, 155301

2009

Published while none of the authors were employed at the CMM

Abstract

We consider classical two-dimensional (2D) Coulomb clusters consisting of two species containing five particles with charge q(1) and five with charge q(2), respectively. Using Monte Carlo and molecular dynamics (MD) simulations, we investigated the ground state configurations as well as radial and angular displacements of particles as a function of temperature and their dependence on the ratio q = q(2)/q(1). We found new configurations and a new multi-step melting behavior for q sufficiently different from the uniform charge limit q = 1.

DOI

http://dx.doi.org/10.1088/0953-8984/21/15/155301

A Chain Model Approach To The Chromium-Based Molecular Rings

Daria — Fri, 16 Nov 2012 19:17:35 +0000

D.M. Tomecka, V. Bellini, F. Troiani, F. Manghi, G. Kamieniarz

Lecture Notes in Computer Science

6127

2008

Published while none of the authors were employed at the CMM

Abstract

We present the electronic and magnetic properties of the antiferromagnetic Cr8 molecular ring (i.e. [Cr8F8Piv16], where HPiv - pivalic acid, trimethyl acetic acid) found by means of density functional theory (DFT) simulation techniques. The all-electron linearized augmented plane wave method (LAPW) implemented in the Wien2k package is exploited. It is also used to calculate the electronic structure, to estimate the exchange coupling parameter and to analyse magnetic anisotropy of an infinite chain model systems corresponding to the Cr8 ring. We demonstrate that the chain models mimic with good approximation the electronic and magnetic properties of the original Cr8 molecule. They reduce substantially computational complexity and speed up extensive investigations of molecules belonging to the Cr-based molecular rings family.

DOI

http://dx.doi.org/

Application of the package SIESTA to linear models of a molecular chromium-based ring

Daria — Fri, 16 Nov 2012 18:38:26 +0000

T. Slusarski, B. Brzostowski, D.M. Tomecka, G. Kamieniarz

Acta Physica Polonica A

118, 5

2010

Published while none of the authors were employed at the CMM

Abstract

We investigate for the first time the electronic and magnetic properties of the linear models of Cr(8)F(8)(Piv)(16) molecular ring using the SIESTA package In the first step the proper values of the SIESTA parameters and the optimal basis set needed for the convergence of the total energy are established Next the estimates of the magnetic coupling J confirming the previous density functional theory calculations are presented.

DOI

http://dx.doi.org/

Ground state configurations and melting of two-dimensional non-uniformly charged classical clusters

Daria — Fri, 16 Nov 2012 18:29:54 +0000

D.M. Tomecka, G. Kamieniarz, B. Partoens, F.M. Peeters

Journal of Physics: Condensed Matter

21, 15, 155301

2009

Published while none of the authors were employed at the CMM

Abstract

DOI

http://dx.doi.org/10.1088/0953-8984/21/15/155301