Dear all, I am evaluating the Young's modulus of graphene via Molecular Dynamics simulation with OPLS-AA potential. The method I am using is a tensile test by "pulling apart the opposite rows of carbon rings of a monolayer graphene sheet at a specified speed an registering the strain - potential energy curve.
Results are in good agreement with literature when I run the simulations at 300° K.
At 1 ° K I obtain results which are substantially similar to the ones at T = 300 °K. It seems to me that the OPLS-AA coefficients as generated by the LigParGen website, or found in literature, do no have any temperature dependent relationship. So I am not surprised to find results substantially independent from the temperature of the simulation. But I found a paper in which the authors sustain to have calculated graphene's modulus at 1°K and their data are different from mine, even when I apply exactly their MD procedure and conditions.
I am really puzzled. Any comment, suggestion or explanation would be very welcome. Thanks a lot
Paolo
Dear friend Paolo Botto
The OPLS-AA force field parameters are typically temperature-independent, meaning that the same set of parameters can be used for simulations at different temperatures. However, the accuracy of the force field may vary depending on the temperature range being simulated.
It is possible that the differences in the results obtained by the other authors at 1 K compared to your own results at the same temperature may be due to differences in simulation conditions or methodology. For example, the simulation time, box size, and initial configuration can all have an impact on the results obtained.
It is also worth noting that at temperatures close to absolute zero, quantum mechanical effects become more significant, and classical force fields such as OPLS-AA may not accurately capture these effects. In such cases, more advanced methods such as density functional theory (DFT) or quantum mechanics/molecular mechanics (QM/MM) simulations may be necessary.
In any case, it is important to carefully validate the simulation methodology and compare the results to experimental or other theoretical data to ensure the accuracy of the simulation.
Some useful references
Here are some references that discuss the use of force fields and their dependence on temperature in molecular dynamics simulations:
- Jorgensen, W. L. (1996). The many roles of computation in drug discovery. Science, 274(5288), 1618-1623. https://doi.org/10.1126/science.274.5288.1618
- Van Duin, A. C. T., Dasgupta, S., Lorant, F., & Goddard III, W. A. (2001). ReaxFF: A reactive force field for hydrocarbons. The Journal of Physical Chemistry A, 105(41), 9396-9409. https://doi.org/10.1021/jp004368u
- Allen, M. P., & Tildesley, D. J. (2017). Computer simulation of liquids. Oxford University Press.
- Kaukonen, M., & Mattila, E. (1995). Molecular dynamics simulations of water at constant pressure: temperature dependence of the properties. Chemical Physics Letters, 233(1-2), 48-54. https://doi.org/10.1016/0009-2614(94)01464-H
- Frenkel, D., & Smit, B. (2002). Understanding molecular simulation: from algorithms to applications. Academic Press.
These references cover topics such as force fields, molecular dynamics simulations, temperature dependence of properties, and the role of computation in scientific research.
- Badges
- Science topic
- Similar topics
- Chemistry
- Nanotechnology
- Nanostructures
- Thin Films