Minina Elena S, Pyanzina Elena S, Novak Ekaterina V, Kantorovich Sofia S
Faculty of Physics, University of Vienna, Boltzmanngasse 5, Vienna, Austria.
Ural Federal University, Lenin av. 51, Ekaterinburg, Russia.
Eur Phys J E Soft Matter. 2018 May 25;41(5):67. doi: 10.1140/epje/i2018-11678-7.
This paper addresses a computational method aimed at obtaining the isothermal compressibility of ferrofluids by means of molecular dynamics (MD) simulations. We model ferrofluids as a system of dipolar soft spheres and carry out MD simulations in the NPT ensemble. The obtained isothermal compressibility computed via volume fluctuations provides us with a strong evidence that dipolar interactions lead to a higher compressibility of dipolar soft sphere systems: the stronger the dipolar interactions, the bigger is the deviation of the compressibility from the one of a system with no dipoles. Furthermore, we use the isothermal compressibility to calculate the structure factor of ferrofluids at low values of wave vectors, i.e. in the range where it is difficult to predict its behaviour because of a problem with accounting for long-range particle correlations that give the main contribution to the structure factor in this range. Our approach based on the interpolation of the structure factor and the computed isothermal compressibility allows us to obtain the smooth structure factor in the range of low wave vectors and the reliable fractal dimension of the clusters formed in the system.
本文介绍了一种计算方法，旨在通过分子动力学（MD）模拟获得铁磁流体的等温压缩率。我们将铁磁流体建模为偶极软球系统，并在NPT系综中进行MD模拟。通过体积涨落计算得到的等温压缩率为我们提供了有力证据，表明偶极相互作用导致偶极软球系统具有更高的压缩率：偶极相互作用越强，压缩率相对于无偶极系统的偏差就越大。此外，我们利用等温压缩率来计算低波矢下铁磁流体的结构因子，即在该范围内由于难以考虑对结构因子起主要贡献的长程粒子相关性问题而难以预测其行为。我们基于结构因子插值和计算得到的等温压缩率的方法，使我们能够在低波矢范围内获得平滑的结构因子以及系统中形成的团簇的可靠分形维数。
