container for atomic derivative information.

An object which contains derivatives with respect to atomic position. 

constructor:
  DerivList()

Methods

  
  init(simulation) - allocate and zero array corresponding to the specified
                     <m simulation>.Simulation.

  clear()          - zero out all existing arrays.

  get(simulation)  - returns a <m cdsVector>.CDSVector_Vec3 corresponding
                     to the derivatives of coordinates in the specified
 		     <m simulation>.Simulation.