BE Polyelectrolyte errors

[butler]

Sylvain Prevost sent the following in November 2017 (subsequently lost and refound) regarding problems with this model. He believes there are two problems:

• In the python code: concentration is rescaled from mol/dm³ to 1/A³ only for monomer concentration, not for salt concentration. Further, polymer concentration is probably a misnomer for monomeric units concentration

• In the docs:
  • The definition of r₀² is wrong, { b/√(48 pi Lb) } should be in the numerator, not the denominator: r₀² = b / [ α √(Ca 48 pi Lb) ]
• in the main equation, it should read r₀⁴, not r₀²
• in the docs, the conversion of concentration from mol/dm³ to 1/A³ should be explicitly indicated before any equation
• for consistency, in the main equation, it should read (q² - 12 h/NA Ca / b²) where NA is Avogadro's constant (as h is supposedly in A³/mol, and assuming Ca has been converted to 1/A³