FTP, often symbolized by either phi or G, identify this type of free energy named for an American physicist.
For a uniformly magnetized sample, where H is the magnetic field strength, this quantity can be defined as F - HMV.  In an ordinary system, its proper variables are temperature and pressure, and it equals F + PV, where F is the Helmholtz free energy.  For a reaction, if the change in this quantity is negative, then the reaction will be spontaneous.  FTP, often symbolized by either phi or G, identify this type of free energy named for an American physicist.
For a uniformly magnetized sample, where H is the magnetic field strength, this quantity can be defined as F - HMV.  
Gibbs free energy (or Gibbs potential)