Molecule Polymer Linear (continuous)
=====================================

Arguments:

  * `nmolecule` (int) - Number of molecules in simulation
  * `moleculeX` (json object) - Information about `moleculeX` where `X` ranges from 0 to `nmolecule-1`. In each `moleculeX` object the following must be specified:

    * `type` (string) - Type of molecule. Here `PolymerLinear`
    * `label` (string) - label for this molecule, defaults to `molX` 
    * `chain_type` (string) - Type of chain statistics. Either `continuous` (as documented here) or `discrete`.
    * `alpha` (float) - Relative length of molecule. :math:`\alpha = N / N_{ref}`
    * `ds` (float) - Contour step size
    * `volume_frac` (float) - Volume fraction of `moleculeX` in the simulation. Must be 0-1.
    * `ncopies` (float) - number of copies of `moleculeX` in the simulation. Note that either `volume_frac` or `ncopies` can be specified, not both. 
    * `nblocks` (int) - Number of blocks in polymer
    * `block_species` (list string) - the species of each block. Length is `nblocks`. Must corresponds to a `label` entry in :ref:`Species`.
    * `block_fractions` (list float) - fractional length of each block. Length is `nblocks`, must sum to 1.

Example (python)::

  fts.add_molecule(alpha=1.0,ds=0.01,nblocks=2,block_fractions=[0.5, 0.5],block_species=['A', 'B'],type='PolymerLinear',chain_type='continuous',volume_frac=1.0)

Example (json)::

  "molecules": {
    "molecule0": {
      "alpha": 1.0,
      "ds": 0.01,
      "nblocks": 2,
      "block_fractions": [0.5, 0.5],
      "block_species": ["A","B"],
      "type": "PolymerLinear",
      "chain_type": "continuous",
      "volume_frac": 1.0
    },
    "nmolecule": 1
  },




Molecule Polymer Continuous Formalism
--------------------------------------

TODO should consolidate. For now, see :ref:`Continuous vs Discrete Chains`.