Employing SAFT Coarse-Grained Force Fields for the Molecular Simulation of Thermodynamic and Transport Properties of CO2–n-Alkane Mixtures

2019 ◽  
Vol 65 (3) ◽  
pp. 1159-1171
Author(s):  
Lingru Zheng ◽  
Fernando Bresme ◽  
J. P. Martin Trusler ◽  
Erich A. Müller
Author(s):  
Hiroki Nagashima ◽  
Takashi Tokumasu ◽  
Shin-ichi Tsuda ◽  
Nobuyuki Tsuboi ◽  
Mitsuo Koshi ◽  
...  

In this paper, we estimated the thermodynamic and transport properties of cryogenic hydrogen using classical molecular simulation to clarify the limit of classical method on the estimation of those properties of cryogenic hydrogen. Three empirical potentials, the Lennard-Jones (LJ) potential, two-center Lennard-Jones (2CLJ) potential, and modified Buckingham (exp-6) potential, and an ab initio potential model derived by the molecular orbital (MO) calculation were applied. Molecular dynamics (MD) simulations were performed across a wide density-temperature range. Using these data, the equation of state (EOS) was obtained by Kataoka’s method, and these were compared with NIST (National Institute of Standards and Technology) data according to the principle of corresponding states. Moreover, we investigated transport coefficients (viscosity coefficient, diffusion coefficient and thermal conductivity) using time correlation function. As a result, it was confirmed that the potential model has a large effect on the estimated thermodynamic and transport properties of cryogenic hydrogen. On the other hand, from the viewpoint of the principle of corresponding states, we obtained the same results from the empirical potential models as from the ab initio potential, showing that the potential model has only a small effect on the reduced EOS: the classical MD results could not reproduce the NIST data in the high-density region. This difference is thought to arise from the quantum effect in actual liquid hydrogen.


2021 ◽  
Author(s):  
Joe G Greener ◽  
David T Jones

AbstractFinding optimal parameters for force fields used in molecular simulation is a challenging and time-consuming task, partly due to the difficulty of tuning multiple parameters at once. Automatic differentiation presents a general solution: run a simulation, obtain gradients of a loss function with respect to all the parameters, and use these to improve the force field. This approach takes advantage of the deep learning revolution whilst retaining the interpretability and efficiency of existing force fields. We demonstrate that this is possible by parameterising a simple coarse-grained force field for proteins, based on training simulations of up to 2,000 steps learning to keep the native structure stable. The learned potential matches chemical knowledge and PDB data, can fold and reproduce the dynamics of small proteins, and shows ability in protein design and model scoring applications. Problems in applying differentiable molecular simulation to all-atom models of proteins are discussed along with possible solutions. The learned potential, simulation scripts and training code are made available at https://github.com/psipred/cgdms.


2005 ◽  
Vol 228-229 ◽  
pp. 15-20 ◽  
Author(s):  
Ioannis G. Economou ◽  
Vasilios E. Raptis ◽  
Vasilios S. Melissas ◽  
Doros N. Theodorou ◽  
John Petrou ◽  
...  

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0256990
Author(s):  
Joe G. Greener ◽  
David T. Jones

Finding optimal parameters for force fields used in molecular simulation is a challenging and time-consuming task, partly due to the difficulty of tuning multiple parameters at once. Automatic differentiation presents a general solution: run a simulation, obtain gradients of a loss function with respect to all the parameters, and use these to improve the force field. This approach takes advantage of the deep learning revolution whilst retaining the interpretability and efficiency of existing force fields. We demonstrate that this is possible by parameterising a simple coarse-grained force field for proteins, based on training simulations of up to 2,000 steps learning to keep the native structure stable. The learned potential matches chemical knowledge and PDB data, can fold and reproduce the dynamics of small proteins, and shows ability in protein design and model scoring applications. Problems in applying differentiable molecular simulation to all-atom models of proteins are discussed along with possible solutions and the variety of available loss functions. The learned potential, simulation scripts and training code are made available at https://github.com/psipred/cgdms.


2014 ◽  
Vol 141 (23) ◽  
pp. 234507 ◽  
Author(s):  
Gustavo A. Orozco ◽  
Othonas A. Moultos ◽  
Hao Jiang ◽  
Ioannis G. Economou ◽  
Athanassios Z. Panagiotopoulos

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