Chapter 15: Simulation of Soft-Matter Systems

Question 1

Examples of Soft-Matter

Answer 1

proteins, membranes, polymers, colloids, liquid crystals

Question 2

Polymer Model Goals

Answer 2

measure diffusion or other thermodynamic observables in corase-grained models

Question 3

End-to-End Distance and Radius of Gyration

Answer 3

• End-to-End Distance:
  
  • gives information about spatial extension of polymer
• Radius of Gyration:
  
  • gives information about density (i.e. how curled-up is the polymer)

Question 4

Ideal Chain Polymer

Answer 4

• no long-range interaction (i.e. freely jointed chain)
• random walk model
• nearest-neighbor interactions only

Question 5

Types of Solvent

Answer 5

statistics of polymer depend on the solubility of polymer in solvent

1. Θ-Solvent
2. Good Solvent
3. Poor Solvent
4. FENE Model

Question 6

Θ-Solvent

Answer 6

• implicit solvent
• ideal chain model
• harmonic potential

Question 7

Good Solvent

Answer 7

• monomers have size → excluded volume interactions
  
  • from WCA potential

Question 8

Poor Solvent

Answer 8

• LJ interaction

Question 9

FENE Model

Answer 9

• finitely extensible non-linear elastic model
• uses non-linear springs

Question 10

Flory Exponent

Answer 10

characterizes the scaling of radius of gyration

Question 11

Flory Exponent for Solvent Types

Answer 11

Question 12

Lattice Models

Answer 12

model polymers on a lattice

Question 13

Polyelectrolyte

Answer 13

charged polymer with fractional charges

• include Coulomb interactions
• can write in terms of Bjerrum length

Question 14

Bjerrum Length

Answer 14

separation distance needed such that V_Coul = kT

Question 15

Polyelectrolyte T=0 Groundstate and Flory Exponent

Answer 15

• chain
• ν = 1

Question 16

Blob Theory

Answer 16

• coarse-graining of polymers into megapolymer blobs
• inside blob, physics is that of neutral polymer
• at large length, polymer behaves like blob
• ν = 1