Molecular Dynamics Study of the Elastic Response of Crystalline, Amorphous and Chemically Disordered NiZr2

1990 ◽  
Vol 205 ◽  
Author(s):  
Carlo Massobrio ◽  
Vittorio Rosato ◽  
Francois Willaime
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Elastic Constants ◽  
Order Parameter ◽  
Elastic Response ◽  
Range Order Parameter ◽  
Long Range Order ◽  
Amorphous Phases ◽  
Antisite Defects ◽  
Dynamics Simulations

AbstractWe calculate the shear elastic constants of the alloy NiZr2 by molecular dynamics simulations in the crystalline and amorphous phases as well as upon introduction of antisite defects in the crystal at T=300K. For S (long range order parameter) equal to 0.5, the system is amorphous and C' is larger than the same quantity relative to the crystal whereas C44 and C66 are smaller.

Mechanical properties of cellulose nanofibrils determined through atomistic molecular dynamics simulations

2012 ◽  
Vol 27 (2) ◽  
pp. 282-286 ◽  
Author(s):  
Jukka Ketoja ◽  
Sami Paavilainen ◽  
James Liam McWhirter ◽  
Tomasz Róg ◽  
Juha Järvinen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Elastic Modulus ◽  
Molecular Dynamics Simulations ◽  
Elastic Constants ◽  
Cellulose Nanofibrils ◽  
Amorphous Cellulose ◽  
Cross Sectional ◽  
Elementary Fibrils ◽  
Dynamics Simulations

Abstract We have carried out atomistic molecular dynamics simulations to study the mechanical properties of cellulose nanofibrils in water and ethanol. The studied elementary fibrils consisted of regions having 34 or 36 cellulose chains whose cross-sectional diameter across the fibril was roughly 3.4 nm. The models used in simulations included both crystalline and non-crystalline regions, where the latter were designed to describe the essentials parts of amorphous cellulose nanofibrils. We examined different numbers of connecting chains between the crystallites, and found out that the elastic constants, inelastic deformations, and strength of the fibril depend on this number. For example, the elastic modulus for the whole fibril can be estimated to increase by 4 GPa for each additional connecting chain.

Atomic Migration in Bulk and Thin Film L10 Alloys: Experiments and Molecular Dynamics Simulations

2007 ◽  
Vol 263 ◽  
pp. 41-50 ◽  
Author(s):  
Veronique Pierron-Bohnes ◽  
R.V.P. Montsouka ◽  
Christine Goyhenex ◽  
T. Mehaddene ◽  
Leila Messad ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Long Range ◽  
Range Order ◽  
Magnetic Storage ◽  
Thermodynamic Quantities ◽  
Long Range Order ◽  
Tight Binding Approximation ◽  
Densities Of States ◽  
Dynamics Simulations

Ferromagnetic L10 ordered alloys are extensively studied nowadays as good candidates for high density magnetic storage media due to their high magnetic anisotropy, related to their chemical order anisotropy. Epitaxial thin bilayers NiPt/FePt/MgO(001) have been grown at 700 K and annealed at 800 K and 900 K. At 800 K, the L10 long-range order increases without measurable interdiffusion. At 900 K, the interdiffusion takes place without destroying the L10 long-range order. This surprising observation can be explained by different diffusion mechanisms that are energetically compared using molecular dynamics simulations in CoPt in the second moment tight binding approximation. In addition, the frequencies of the normal modes of vibration have been measured in FePd, CoPt and FePt single crystals using inelastic neutron scattering. The measurements were performed in the L10 ordered structure at 300 K. From a Born-von Karman fit, we have calculated the phonon densities of states. The migration energies in the 3 systems have been estimated using the model developed by Schober et al. (1981). The phonon densities of states have also been used to calculate several thermodynamic quantities as the vibration entropy and the Debye temperature.

Morphological and charge transport properties of amorphous and crystalline P3HT and PBTTT: insights from theory

2015 ◽  
Vol 17 (28) ◽  
pp. 18742-18750 ◽  
Author(s):  
Domenico Alberga ◽  
Aurélie Perrier ◽  
Ilaria Ciofini ◽  
Giuseppe Felice Mangiatordi ◽  
Gianluca Lattanzi ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Charge Carrier ◽  
Dft Calculations ◽  
Charge Transport ◽  
Molecular Dynamics Simulations ◽  
Transport Properties ◽  
Marcus Theory ◽  
Organic Polymers ◽  
Amorphous Phases ◽  
Dynamics Simulations

Molecular dynamics simulations and DFT calculations are combined via Marcus theory to yield an estimate of charge carrier mobilities in the crystalline and amorphous phases of P3HT and PBTTT organic polymers.

Mechanical Properties of Tubulin Molecules by Molecular Dynamics Simulations

2006 ◽  
Author(s):  
So̸ren Enemark ◽  
Marco A. Deriu ◽  
Monica Soncini
Keyword(s):  
Molecular Dynamics ◽  
Elastic Constant ◽  
Molecular Dynamics Simulations ◽  
Elastic Constants ◽  
Interaction Force ◽  
Basic Unit ◽  
Dynamics Simulations ◽  
The Individual ◽  
Explicit Water ◽  
Β Tubulin

The basic unit in microtubules is αβ-tubulin, a hetero-dimer consisting of an α- and a β-tubulin monomer. The mechanical characteristics of the dimer as well as of the individual monomers may be used to obtain new insight into the microtubule tensile properties. In the present work we evaluate the elastic constants of each of the monomers and the interaction force between them by means of molecular dynamics simulations. Molecular models of α-, β-, and αβ-tubulin were developed starting from the 1TUB.pdb structure from the RSCB database. Simulations were carried out in a solvated environment using explicit water molecules. In order to measure the monomers’ elastic constants, simulations were performed by mimicking experiments carried out with atomic force microscopy. A different approach was used to determine the interaction force between the α- and β-monomers using 8 different monomer configurations based on different inter-monomer distances. The obtained results show an elastic constant value for α-tubulin of 3.4–3.9 N/m, while for the β-tubulin the elastic constant was measured to be 1.8–2.4 N/m. The maximum interaction force between the monomers was estimated to be 11.2 nN. In perspective, these outcomes will allow exchanging atomic level description with key mechanical features enabling microtubule characterisation by continuum mechanics approach.

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