目录
- Liquid/Solid Surface-01
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- Some Slip Model
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- PE/Au
- PE/mica
- Oscillatory Couette flows
- Some United-Atom PE Force Field
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- Details of the n-alkanes model
- The well-known (Siepmann-Karaborni-Smit) SKS united-atom potential model
- Capaldi et al.
- Bolten et al.
Liquid/Solid Surface-01
- Polyethylene(PE)
Some Slip Model
PE/Au
Atomistic representations of the PE/Au system at equilibrium (left) and under constant Couette flow (right).
Sgouros AP, Theodorou DN. Atomistic simulations of long-chain polyethylene melts flowing past gold surfaces: structure and wall-slip. Molecular Physics 2020:1–20. https://doi.org/10.1080/00268976.2019.1706775 .
PE/mica
Schematics for confined polymer melts.
Jeong S, Cho S, Kim JM, Baig C. Molecular mechanisms of interfacial slip for polymer melts under shear flow. J. Rheol. 2017;61(2):253–64. https://doi.org/10.1122/1.4974907 .
Oscillatory Couette flows
(Color online) Positions of fluid monomers (open blue circles) and wall atoms (filled gray circles). The upper wall oscillates with the angular frequency x in the ^x direction (indicated by the double-sided arrow), while the lower wall is always stationary
Priezjev NV. Molecular dynamics simulations of oscillatory Couette flows with slip boundary conditions. Microfluid Nanofluid 2013;14(1-2):225–33. https://doi.org/10.1007/s10404-012-1040-5 .
Some United-Atom PE Force Field
Details of the n-alkanes model
Siepmann JI, Karaborni S, Smit B. Simulating the critical behaviour of complex fluids. Nature 1993;365(6444):330–2. https://doi.org/10.1038/365330a0 .
The well-known (Siepmann-Karaborni-Smit) SKS united-atom potential model
| INTERACTION | form | Parameter |
|---|---|---|
| Strectch | U s t r e t c h i n g = k s t r 2 ( l ? l e q ) 2 U_{stretching}=\dfrac{k_{str}}{2}(l-l_{eq})^2 Ustretching?=2kstr??(l?leq?)2 | k s t r / k B = 452900 K / A ? 2 k_{str}/k_B=452900 \ K/\mathring{A}^2 kstr?/kB?=452900 K/A?2 l e q = 1.54 A ? l_{eq}=1.54 \ \mathring{A} leq?=1.54 A? |
| Bending | U b e n d i n g = k b e n 2 ( θ ? θ e q ) 2 U_{bending}=\dfrac{k_{ben}}{2}(\theta-\theta_{eq})^2 Ubending?=2kben??(θ?θeq?)2 | k b e n / k B = 62500 K / r a d 2 k_{ben}/k_B=62500 \ K/rad^2 kben?/kB?=62500 K/rad2 θ e q = 11 4 ? \theta_{eq}=114^\circ θeq?=114? |
| Torsion | U t o r s i o n a l = ∑ m = 0 3 a m c o s m ? U_{torsional}=\sum\limits_{m=0}^{3}a_mcos^m\phi Utorsional?=m=0∑3?am?cosm? | a 0 / k B = 1010 K a_0/k_B=1010 \ K a0?/kB?=1010 K, a 1 / k B = 2019 K a_1/k_B=2019 \ K a1?/kB?=2019 K a 2 / k B = 136.4 K a_2/k_B=136.4 \ K a2?/kB?=136.4 K, a 3 / k B = ? 3165 K a_3/k_B=-3165 \ K a3?/kB?=?3165 K |
| Non-bonded | U l j ( r ) = 4 ? i j [ ( σ i j r ) 12 ? ( σ i j r ) 6 ] U_{lj}(r)=4\epsilon_{ij}[(\dfrac{\sigma_{ij}}{r})^{12}-(\dfrac{\sigma_{ij}}{r})^{6}] Ulj?(r)=4?ij?[(rσij??)12?(rσij??)6] | C H 2 : ? / k B = 47 K , σ = 3.93 A ? CH_2: \epsilon/k_B=47 \ K, \sigma=3.93 \ \mathring{A} CH2?:?/kB?=47 K,σ=3.93 A? C H 3 : ? / k B = 114 K , σ = 3.93 A ? CH_3: \epsilon/k_B=114 \ K, \sigma=3.93 \ \mathring{A} CH3?:?/kB?=114 K,σ=3.93 A? |
Baig C, Mavrantzas VG, Kr?ger M. Flow Effects on Melt Structure and Entanglement Network of Linear Polymers: Results from a Nonequilibrium Molecular Dynamics Simulation Study of a Polyethylene Melt in Steady Shear. Macromolecules 2010;43(16):6886–902. https://doi.org/10.1021/ma100826u .
这篇论文描述的参数并不能直接输入至LAMMPS里,需要进行一下单位换算，推荐一个 单位转换工具，换算后的结果如下：
k s t r = 900 k c a l / m o l / A ? 2 k_{str}=900 \ kcal/mol/ \mathring{A}^2 kstr?=900 kcal/mol/A?2
k b e n d = 124.2 k c a l / m o l / A ? 2 k_{bend}=124.2 \ kcal/mol/ \mathring{A}^2 kbend?=124.2 kcal/mol/A?2
a 0 = 2 k c a l / m o l , a 1 = 4.01 k c a l / m o l , a 2 = 0.271 k c a l / m o l , a 3 = ? 6.29 k c a l / m o l a_0=2 \ kcal/mol, a_1=4.01 \ kcal/mol, a_2=0.271 \ kcal/mol, a_3=-6.29 \ kcal/mol a0?=2 kcal/mol,a1?=4.01 kcal/mol,a2?=0.271 kcal/mol,a3?=?6.29 kcal/mol
C H 2 : ? = 0.0933 k c a l / m o l , C H 3 : ? = 0.2265 k c a l / m o l CH_2: \epsilon=0.0933 \ kcal/mol, CH_3: \epsilon=0.2265 \ kcal/mol CH2?:?=0.0933 kcal/mol,CH3?:?=0.2265 kcal/mol
Capaldi et al.
Capaldi FM, Boyce MC, Rutledge GC. Molecular response of a glassy polymer to active deformation. Polymer 2004;45(4):1391–9. https://doi.org/10.1016/j.polymer.2003.07.011 .
Bolten et al.
Ko MJ, Waheed N, Lavine MS, Rutledge GC. Characterization of polyethylene crystallization from an oriented melt by molecular dynamics simulation. J Chem Phys 2004;121(6):2823–32. https://doi.org/10.1063/1.1768515 .