Molecular Dynamics Study of the Structure in Vitreous Silica with COMPASS Force Field at Elevated Temperatures

2007 ◽  
Vol 546-549 ◽  
pp. 2189-2193 ◽  
Author(s):  
Yuan Fa Ding ◽  
Yue Zhang ◽  
Fan Wei Zhang ◽  
Da Hai Zhang ◽  
Zhong Ping Li
Keyword(s):  
Molecular Dynamics ◽  
Force Field ◽  
Elevated Temperatures ◽  
Bond Angle ◽  
Vitreous Silica ◽  
Resistant Material ◽  
Calculated Density ◽  
Sio4 Tetrahedron ◽  
Structure Correlations ◽  
Dynamics Method

Vitreous silica, as high temperature resistant material, has not been completely studied with the influence of extreme working conditions due to experimental limitations. In this work, the structure correlations of vitreous silica were investigated by molecular dynamics method at elevated temperatures from 0 K to 4000 K. COMPASS force field was firstly used in simulating vitreous silica. The temperature dependence of volume for vitreous silica was studied and a maximum of volume was found. The calculated density and the thermal expansion coefficient are close to experimental results. The evolutions of structure in thermal history were discussed in detail. The correlations between the average Si-O bond length and the Si-O-Si bond angle is shown in agreement with the studies used other potentials in literatures. It is proved that the COMPASS force field is appropriate for simulating vitreous silica in some extent, especially in depicting the Si-O interaction and the [SiO4] tetrahedron. Finally, the origin of the volume maxima was discussed based on the analysis of the structure.

scholarly journals Reactive Molecular Dynamics Study of the Thermal Decomposition of Phenolic Resins

2019 ◽  
Vol 3 (2) ◽  
pp. 32 ◽  
Author(s):  
Marcus Purse ◽  
Grace Edmund ◽  
Stephen Hall ◽  
Brendan Howlin ◽  
Ian Hamerton ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Thermal Decomposition ◽  
Force Field ◽  
Elevated Temperatures ◽  
Phenol Formaldehyde ◽  
Phenolic Resins ◽  
Reactive Molecular Dynamics ◽  
Atomistic Models ◽  
Suitable Combination ◽  
Experimental Values

The thermal decomposition of polyphenolic resins was studied by reactive molecular dynamics (RMD) simulation at elevated temperatures. Atomistic models of the polyphenolic resins to be used in the RMD were constructed using an automatic method which calls routines from the software package Materials Studio. In order to validate the models, simulated densities and heat capacities were compared with experimental values. The most suitable combination of force field and thermostat for this system was the Forcite force field with the Nosé–Hoover thermostat, which gave values of heat capacity closest to those of the experimental values. Simulated densities approached a final density of 1.05–1.08 g/cm3 which compared favorably with the experimental values of 1.16–1.21 g/cm3 for phenol-formaldehyde resins. The RMD calculations were run using LAMMPS software at temperatures of 1250 K and 3000 K using the ReaxFF force field and employing an in-house routine for removal of products of condensation. The species produced during RMD correlated with those found experimentally for polyphenolic systems and rearrangements to form cyclopropane moieties were observed. At the end of the RMD simulations a glassy carbon char resulted.

Molecular Dynamics Simulation of Void Structures in Vitreous Silica

2014 ◽  
Vol 893 ◽  
pp. 80-86
Author(s):  
Yuan Fa Ding ◽  
Zhi Min Guo ◽  
Xiang Dong Su ◽  
Yue Zhang
Keyword(s):  
Molecular Dynamics ◽  
Thermal Expansion ◽  
Long Range ◽  
Elevated Temperatures ◽  
Negative Thermal Expansion ◽  
Vitreous Silica ◽  
Dynamics Simulation ◽  
Small Radius ◽  
Large Void ◽  
Density Anomaly

In order to investigate the density anomaly of vitreous silica in the medium-or long-range order, different models were made to study the atomic configuration revolution in thermal history by molecular dynamics. The void structures have been studied through analyzing the best model that is carefully selected. The principle of void size distribution revolution at elevated temperatures was used to explain the density anomaly of the vitreous silica. The simulation results showed that when the temperature is low, the void radius increases with the temperature rising. After 2000 K, large void structures are destroyed, filled, or separated into small radius voids. In the range from 2000 K to 2400 K, large void structures decrease faster exceeding the bond extension on thermal expansion contribution, this should be the root cause of negative thermal expansion behavior for vitreous silica. When the temperature is greater than 2400 K, with the temperature rising, the normal thermal expansion is recovered gradually because number of large voids has been reduced and their destroying cannot eliminate the contribution to expansion of bond extension. Therefore, the negative thermal expansion of vitreous silica could be described by the revolution of void structures in the medium-or long-range clearly, and is mainly influenced by the existence and change of larger voids.

Study on Interactive Multi-resolution Molecular Dynamics Method

2000 ◽  
Vol 20 (1Supplement) ◽  
pp. 43-46
Author(s):  
Ken-ichi SAITOH ◽  
Takashi DOI ◽  
Masao KOMAYA ◽  
Takehiko INABA
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Method ◽  
Dynamics Method
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