Chapter 4: MD Example Flashcards Preview

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Flashcards in Chapter 4: MD Example Deck (6):
1

MD Interactions

  • short-range repulsion: Pauli exclusion principle
  • mid-range attraction: dispersion
  • long-range: electrostatics

2

Lennard-Jones Potential

  • one of simplest ways to capture short- and mid-range interactions

3

Lennard-Jones Potential 
(Graph)

  • min{VLJ(r)} = VLJ(21/6) = -ε 

4

Lennard-Jones Potential 
(Cut-off Distance)

  • cannot do infinite integral → introduce cut-off distance rc
    • typically rc = 2.5σ
    • use to shift potential so that VLJ(r>|rc) = 0

5

Simulation Units

  • reduced (dimensionless) units are useful → no rounding errors
  • For mechanical systen, need three independent units
    • e.g. mass, energy, length
      • addition of electrostatics requires fundamental charge eo

6

Law of Corresponding States

Using reduced units allows simulation of a class of systems, rather than specific example-systems