phb

This is Monte Carlo code which automatically follows a given phase boundary.

Input files: (see maps documentation)
  lat.in         (describes the lattice)
  gs_str.out     (lists the ground states)
  eci.out        (ECI)
  clusters.out    (clusters)

You have to provide, on the command line, the following parameters:

-The two phases which are in equilibrium.
  For instance,
    -gs1=0 -gs2=1
  If there are n ground states, phases are numbered from 0 to n-1 .
  These ground states are read in from gs_str.out
  The disordered state is labelled by the number -1.

  If the two phases are on different lattices, you need to specify
  the path that give access to the files 
    lat.in
    gs_str.out
    eci.out
    clusters.out
  for each lattice. For instance
   -d1=../fcc/ -d2=../hcp/
  If either or both options are omitted, the files are read from the
  current directory.
  
-The starting temperature and chemical potential
  for instance,
  -T=100 -mu=0.125
  (Make sure to set blotzmann's constant appropriately.)
  (If you tracing the phase boundary between two ordered phases, starting from
  0K, you do not need to specify a starting T and mu.)

-The temperature step
  for instance -dT=50

-The 'enclosed radius', which sets the system size
  for instance, -er=35
  (see emc2 documentation for more information)

-The precision of the calculation
 This is expressed as the desired precision of the average concentration.
  For instance, -dx=1e-3
 The code automatically finds the equilibration time and the number
 Monte Carlo steps needed to obtain the target standard deviation
 of the average concentration.

There are a number of optional parameters as well.

 -ltep: The low temperature expansion is used to find the free energy
  at low temperature. -ltep gives the maximum error allowed before
  Monte Carlo is used instead of LTE.

 -dmu: The step in chemical potential used when scanning in search
  of the phase boundary.
  for instance, -dmu=0.005
  Sometimes, the algorithm looses track of the phase boundary
  (because of statistical errors). When that happens, it scans
  a range of values of the chemical potential in search of the
  boudary of the hysteresis loop associated with the first
  order transition of interest. It then position itself in the
  middle of it. dmu is the step size used for that search.
  Note that the code will automatically shrink dmu if needed.
  By default, dmu is automaticaly set to the formation energy
  of a disordered alloy times 0.01.

  -mug lets you specify a small difference in chemical potential 
  between the phases, to make the code less sensitive to accidental
  phase transition.

  -k sets boltzman's constant (see emc2 documentation)
  -keV

  -dn indicates that the boundary must be folowed downward
   (decreasing  T)

Output file:

  Column      Value
  1           temperature
  2           chemical potential
  3           concentration of phase 1 in [-1,1]
  4           concentration of phase 2 in [-1,1]
  5           energy-mu*x for phase 1
  6           energy-mu*x for phase 2