scholarly journals Structural Simulation of Mg2SiO4 under Compression

2020 ◽  
Vol 36 (4) ◽  
Author(s):  
Nguyen Hung Son ◽  
Nguyen Hoang Anh
Keyword(s):  
High Pressure ◽  
Molecular Dynamic ◽  
Molecular Dynamic Method ◽  
Dynamic Method ◽  
Bond Angle ◽  
Distribution Functions ◽  
Radial Distribution Functions ◽  
Angle Distribution ◽  
Peak Splitting ◽  
Bond Angle Distribution

The microstructure in Mg2SiO4 glass under high compression is studied by molecular dynamic method. This work revealed the correlation between pair radial distribution functions (PRDF) of Si-Si pair and bond angle distribution (BAD) of Si-O-Si and focus on clarifying the split peak of Si-Si PRDF. Moreover, visualizing the bonds of Si-Si at different pressures show changing of Si-Si bonds with pressure. In particularly, as increasing pressure, it forms corner-sharing, edge-sharing and face-sharing bond between SiOx coordination units results in the first peak splitting of Si-Si PRDF at high pressure. The results of Si-Si’s PRDF have also been analyzed and explained in detail.

Structure and Properties of the GeAsS Glasses from Ab initio Calculations

2014 ◽  
Vol 1035 ◽  
pp. 502-507
Author(s):  
Li An Chen
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Ab Initio ◽  
Bond Angle ◽  
Distribution Functions ◽  
Dynamics Simulation ◽  
Angle Distribution ◽  
Structure And Properties ◽  
Bond Angle Distribution ◽  
Pair Distribution Functions

The structure and properties of the GexAsxS100-2x have been studied by ab initio molecular dynamics simulation. By calculating the pair distribution functions, bond angle distribution functions, we analyze the structure and properties of the alloys. Calculations show that Ge and As are all well combined with S atoms. When x is smaller than 25.0 the binding increases with x , when x is larger than 25.0 the binding decreases with increasing x . The intervention of As atom does not affect the GeS2 formation in Ge40As40S80

THE CORRELATION BETWEEN BOND ANGLE DISTRIBUTION AND THE COORDINATION OF SILICA LIQUID UNDER PRESSURE

2012 ◽  
Vol 26 (20) ◽  
pp. 1250117 ◽  
Author(s):  
L. T. VINH ◽  
N. V. HUY ◽  
P. K. HUNG
Keyword(s):  
Experimental Data ◽  
Molecular Dynamics ◽  
Bond Angle ◽  
Simple Expression ◽  
Dynamics Simulation ◽  
Angle Distribution ◽  
Bond Angle Distribution ◽  
Simulation Results ◽  
Substantial Change ◽  
Good Agreement

Molecular dynamics simulation is carried out for liquid SiO 2 at pressure ranged from zero to 30 GPa and by using BKS, Born–Mayer type and Morse–Stretch potentials. The constructed models reproduce well the experimental data in terms of mean coordination number, bond angle and pair radial distribution function. Furthermore, the density of all samples can be expressed by a linear function of fractions SiO x. It is found that the topology of units SiO x and linkages OSi y is unchanged upon compression although the liquid undergoes substantial change in its network structure. Consequently, the partial bond angle distribution for SiO x and OSi y is identical for all samples constructed by the same potential. This result allows to establishing a simple expression between total bond angle distribution (BAD) and fraction of SiO x and OSi y. The simulation shows a good agreement between the calculation and simulation results for both total O–Si–O and Si–O–Si BADs. This supports a technique to estimate amount of units SiO x and linkages OSi y on base of total Si–O–Si and O–Si–O BADs measured experimentally.

A Molecular Dynamic Study on the Equation of State for Argon Fluid at Temperatures Near its Critical Point

2014 ◽  
Vol 543-547 ◽  
pp. 3959-3962
Author(s):  
Xiao Bin Lv ◽  
Xiao Feng Yang
Keyword(s):  
Equation Of State ◽  
Molecular Dynamic ◽  
Cluster Expansion ◽  
Simple Form ◽  
Empirical Formula ◽  
Molecular Dynamic Method ◽  
Dynamic Method ◽  
The Third ◽  
Ideal Gases ◽  
Expansion Technique

In this paper, we have developed an empirical formula describing the equation of state of argon fluid using cluster expansion technique and commonly used force parameters. To test the reliability of the formula, we have further simulated the equation of state for argon at corresponding states employing molecular dynamic method. The comparisons have shown that the empirical formula gives much better prediction than that from the simple form equation of ideal gases and the inclusion of the third virial terms in expansions is prominently important.

Interaction of Dislocations at Interfaces in Multilayered Materials

2016 ◽  
Vol 258 ◽  
pp. 102-105
Author(s):  
Hideo Koguchi ◽  
Yusuke Tanaka
Keyword(s):  
Boundary Condition ◽  
Surface Tension ◽  
Molecular Dynamic ◽  
Continuum Mechanics ◽  
Misfit Dislocation ◽  
Molecular Dynamic Method ◽  
Dynamic Method ◽  
Substrate Interface ◽  
Interface Elasticity ◽  
Multilayered Materials

The authors construct a bridge between a microscale view and a nanoscale one in continuum mechanics. When the size of structure reduces to nanolevel, the ratio of surface to volume increases. Then, the surface stresses, which like to surface tension in fluid, influence on bulk stresses. In the present paper, the authors analyze a problem that anisotropic nanothin layers are deposited on a half substrate. Interface stresses and interface elasticity are taken into account for the boundary condition for each layer. Furthermore, misfit dislocation networks which generate from a mismatch of lattice parameters in crystals composing multilayers exist at each interface. A complicated interaction between misfit dislocation networks located at different interfaces will be demonstrated, and the results in the theory will be compared with those in a molecular dynamic method using a generalized embedded atomic potential.

Monte Carlo simulation of isopentane glass

1985 ◽  
Vol 400 (1818) ◽  
pp. 61-73 ◽  
Keyword(s):  
Monte Carlo ◽  
Radial Distribution ◽  
Glassy State ◽  
Distribution Functions ◽  
Intermolecular Potential ◽  
Radial Distribution Functions ◽  
Angle Distribution ◽  
Geometrical Factors ◽  
Experimental Values ◽  
Energy Distribution Functions

Monte Carlo calculations on liquid and glassy isopentane have been performed by using transferable intermolecular potential functions (t. i. ps). Thermodynamic properties, radial distribution functions, coordination number distributions, etc., calculated for the liquid are in reasonable agreement with the experimental values. By quenching the liquid, we have obtained the glass-transition temperature from the temperature variation of intermolecular energy, volume and the heat of vaporization. Radial distribution functions suggest a structure of the glass primarily influenced by geometrical factors and with no preference for any particular orientation ; the peak around 4.0 Å (1 Å = 10 -10 m = 10 -1 nm) between the more exposed carbon atoms seems to be the characteristic of densely packed hydrocarbons. The histogram of the nearest-neighbour distribution shows a shift towards higher coordination in the glassy state. Interesting differences are found between the liquid and the glass in the dimerization energy and bonding energy distribution functions. Narrower distribution is found on vitrification in the dihedral angle distribution function for rotation around the central C–C bond.

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