Spliced soft-core interaction potential for filling small-scale enclosures

Patent metadata

Field	Value
Publication number	US-2020302098-A1
Application number	US-202016823261-A
Country	US
Kind code	A1
Filing date	Mar 18, 2020
Priority date	Mar 18, 2019
Publication date	Sep 24, 2020
Grant date	—

Abstract

A molecular dynamics system employing a spliced soft-core potential (the “MD/SSCP”) facilitates studying the arrangement of particles in an enclosure and/or near an interface. In some embodiments, the MD/SSCP initializes a three-dimensional representation containing the enclosure and the particles in a first arrangement. The MD/SSCP conducts a first simulation to transition the representation to a second arrangement, during which the particles are allowed to move through a wall of the enclosure while the SSCP is unengaged. The MD/SSCP conducts a second simulation to transition the representation to a third arrangement, during which it becomes more difficult for the particles to move through the wall of the enclosure while the SSCP is gradually engaged. The MD/SSCP conducts a third simulation to transition the representation to a fourth arrangement of the particles, during which it becomes almost impossible for the particles to move through the wall of the enclosure.

First claim

We claim:

1 . A method performed by one or more computing systems for simulating an arrangement of particles within an enclosure, the method comprising:
initializing a three-dimensional representation containing the enclosure and the particles, wherein the particles are represented in a first arrangement in which the particles are distributed throughout the three-dimensional representation and allowed to overlap with the enclosure; conducting a first simulation stage to transition the three-dimensional representation from the first arrangement to a second arrangement of the particles, wherein the particles are allowed to move through a wall of the enclosure during the first simulation stage under the assumption that no repulsive force between the particles and the enclosure is engaged; and conducting a second simulation stage to transition the three-dimensional representation from the second arrangement to a third arrangement of the particles, wherein the particles are allowed to move through the wall of the enclosure during the second simulation stage under the assumption that only a fraction of the repulsive force between the particles and the enclosure is engaged.

2 . The method of claim 1 wherein:
the first simulation stage includes simulated annealing of the particles to raise a temperature of the simulated system from a first temperature to a second temperature and raise a pressure of the simulated system from a first pressure to a second pressure;
the second simulation stage includes ramping up a spliced soft-core potential while the simulated system is at the second temperature and the second pressure.

3 . The method of claim 2 , further comprising conducting a third simulation stage with respect to the simulated system to transition the three-dimensional representation from the third arrangement to a fourth arrangement of the particles, wherein the third simulation stage includes simulated annealing of the particles to decrease the temperature of the simulated system from the second temperature to a third temperature and decrease the pressure from the second pressure to a third pressure.

4 . The method of claim 1 wherein:
the first simulation stage includes long range slow growth thermodynamic integration using a long-range section of a spliced soft-core potential; and
the second simulation stage includes short range slow growth thermodynamic integration using a complete spliced soft-core potential.

5 . The method of claim 1 , further comprising analyzing the simulated system in the third state to determine one or more metrics about the particles.

6 . A method performed by one or more computing systems for simulating an arrangement of particles within an enclosure, the method comprising:
generating a representation of the particles and the enclosure, wherein the particles are represented in a bulk material system and the enclosure is represented in an enclosure system; modifying the representation so that the particles are represented as being equilibrated at a first temperature and a first pressure in the bulk material system; modifying the representation so that the enclosure is represented as being equilibrated at the first temperature and the first pressure in the enclosure system; modifying the representation so that the bulk material system and the enclosure system are represented as being overlapped in an overlapped system at the first temperature and the first pressure; modifying the representation so that the overlapped system is represented as heated and pressurized to a second temperature higher than the first temperature and a second pressure higher than the first pressure; modifying the representation so that the overlapped system is represented with a spliced soft-core potential affecting interactions between the enclosure and the particles by transitioning the spliced soft-core potential from an unengaged state to an engaged state; and modifying the representation so that the overlapped system is represented as cooled and depressurized to a third temperature lower than the second temperature and a third pressure lower than the second pressure with the spliced soft-core potential between the enclosure and the particles engaged.

7 . The method of claim 6 , further comprising modifying the representation so that the overlapped system is represented with a hard-core potential affecting interactions between the enclosure and the particles after the representation of the overlapped system is cooled and depressurized to the third temperature and the third pressure.

8 . The method of claim 6 , wherein modifying the representation so that the overlapped system is represented as heated and pressurized comprises separately thermostating the representation of the particles and the representation of the enclosure such that only the representation of the particles are heated and pressurized.

9 . The method of claim 7 , further comprising modifying the representation so that the particles and the enclosure in the overlapped system are represented equilibrated at the third temperature and the third pressure after modifying the overlapped system such that the overlapped system is represented with a hard-core potential affecting interactions between the enclosure and the particles.

10 . The method of claim 8 wherein modifying the representation so that the overlapped system is represented as heated and pressurized is configured to modify the representation of the pressure the particles to maintain a constant density in the particles during annealing.

11 . The method of claim 6 wherein the spliced soft-core potential is given by Equation 1.

12 . The method of claim 7 wherein the hard-core potential is a 6-12 Lennard-Jones potential.

13 . The method of claim 7 wherein the hard-core potential is given by Equation 3 when λ=1.

14 . The method of claim 6 , further comprising recording one or more metrics on the representation of the particles contained in the representation of the enclosure after the representation of the overlapped system reaches the third temperature and the third pressure.

15 . The method of claim 14 wherein the one or more metrics include:
the number of particles represented as contained in the enclosure;
the position of the particles represented as contained in the enclosure; and
the radial density of the particles represented as contained in the enclosure.

16 . A method performed by one or more computing systems for simulating an arrangement of an ionic liquid within a carbon nanotube, the method comprising:
generating a representation of the ionic liquid in a bulk material system and the carbon nanotube in an enclosure system; modifying the representation so that the ionic liquid is represented as being equilibrated at a first temperature and a first pressure in the bulk material system; modifying the representation so that the carbon nanotube is represented as being equilibrated at the first temperature and the first pressure in the enclosure system; modifying the representation so that the bulk material system and the enclosure system are represented as being overlapped in an overlapped system at the first temperature and the first pressure; modifying the representation so that the ionic liquid is represented as heated and pressurized to a second temperature higher than the first temperature and a second pressure higher than the first pressure; modifying the representation so that the overlapped system is represented with a spliced soft-core potential affecting interactions between molecules in the ionic liquid and

Assignees

• L Livermore Nat Security Llc
• Univ California

Inventors

• Meshot Eric
• Bernardi Austen
• Faller Roland

Classifications

• G06F30/367

  Design verification, e.g. using simulation, simulation program with integrated circuit emphasis [SPICE], direct methods or relaxation methods · CPC title

• G06F30/25 Primary

  using particle-based methods · CPC title

• G06F2119/14

  Force analysis or force optimisation, e.g. static or dynamic forces · CPC title

• G06F2111/10

  Numerical modelling · CPC title