Virtual member functions

• virtual int create(void) - the main virtual routine provided by this class. This is used after a new Molecule subclass has been created (with the required information for reading the molecule given in the constructor). Initially the Molecule is empty; to initialize it, the create() routine is called which will then start the actual process of reading in the data. Each version of create() supplied by the derived classes should, after doing it's own creation, call the create() routine in the parent class. This routine returns the success of the creation operation.
• virtual float scale_factor(void) - returns (possibly calculating first) the scaling factor required to scale the coordinates for the current timestep to fit in a box from -1 ... 1 in all dimensions.
• virtual void cov(float &, float &, float &) - return the position of the center of volume of the current coordinate set.