robustrelax-vasp

This command implements the "inflection-detection" method introduced in
A. van de Walle, Q. Hong, S. Kadkhodaei and R. Sun, "The free energy of mechanically unstable 
                     phases"
Nat. Com. 6, 7559 (2015) doi:10.1038/ncomms8559 .
and
A. van de Walle and S. Kadkhodaei and R. Sun and Q.-J. Hong, "Epicycle method for elasticity limit 
                     calculations",
Phys. Rev. B 95 144113 (2017) doi:10.1103/PhysRevB.95.144113 .

It calculates the energy of a structure that is potentially mechanically unstable.
In a nutshell: the method finds either a local minimum (for a mechanically stable phase)
or the inflection point on a path joining the unrelaxed and fully relaxed structures
(for a mechanically unstable phase).

Syntax: robustrelax_vasp [options] command_prefix
where options are
  -id             Inflection Detection method
  -idop "options" Options passed to the infdet command.
  -neb            Use the Nudged Elastic Band method to find minimum energy path
                  Otherwise: simply interpolate linearly.
  -ex             Only extract data form VASP files. Do not run anything.
  -c  [real]      Relaxation magnitude cutoff needed to activate robust relax algorithm (default: 
                     0).
  -ni [integer]   Number of images in the minimum energy path (default: 6).
  -rc [string]    Command for full relaxation          (Default: runstruct_vasp -w vasp.wrap).
  -vc [string]    Command for volume only relaxation   (Default: runstruct_vasp -w vaspvol.wrap).
  -cc [string]    Command for chain (neb) calculations (Default: runstruct_vasp -w vaspneb.wrap).
  -sc [string]    Command for static runs              (Default: runstruct_vasp -w 
                     vaspstatic.wrap).
  -ic [string]    Command for inflection-detection runs (-id option) (Default: runstruct_vasp -p -w 
                     vaspid.wrap).
  -idf [real]     Starting point fraction for inflection detection (default: 0.5)
  -ja
  -jc             By how much to jitter atoms (-ja) and cell parameters (-jc) for the initial 
                     conditions
                  for inflection-detection method.
  -vib            Update vibrational data in svib_ht file from vol_0/svib_ht file.
  -mk             Make auxiliary vasp input files (vaspvol.wrap, vaspneb.wrap, vaspstatic.wrap, 
                     vaspf.wrap, vaspid.wrap)
                  from vasp.wrap. Does not run anything.
  -cln            clean files for a full restart.
  -cip            continue (an prior run) if possible (only implemented for -id algorithm).
  -d              Use all defaults values.
  -h              Display more help.
  command_prefix  Prefix needed for vasp to run on a remote machine or in parallel (e.g. mpirun).

Note: the commands specified by -rc,-vc,-cc,-sc can be set to empty "" to skip the corresponding
  calculation step (useful to restart an aborted run).

This command does the following:
1) Fully relax the structure (in str_hint.out or str.out) to create str_relax.out,
   just like runstruct_vasp.
2) If the relaxation cutoff (-c=...) no exceeded, stop. Typically, should be set to -c=0.05.
3) Relax the volume only of structure in str_sup.out or str.out. Results are in directory 00/
4) Do a neb (-neb) or infection detection (-id) calculation between the two structures obtained in 
                     step 1 and 3
   or just a linear interpolation between them (if no -neb or -id). Results are in directories ??/
   Note that you need VTST Tools from http://theory.cm.utexas.edu/vtsttools/ for the neb method
   with variable cell shape.
5) Do static calculations in each directory ??/
6) Find the inflection point on the path optimized in step 4. If it does not exist, find the
   minimum energy along that path.
7) Report the energy found in 6 in the file energy and the corresponding geometry in str_relax.out

Notes:
1) str_beg.out and str_end.out contain the extremities of the path.
   If you want to restart from scratch, delete these files.
2) For high symmetry phases (e.g. bcc,fcc,hcp) you may need to break the symmetry of the phase for 
                     it to relax.
   For that purpose, you can use, e.g.,
      symbrklib W fcc bcc
   or
      cellcvrt -ja=0.01 -jc=0.01 < str.out > str_hint.out .
   Sometimes a supercell is needed (a phonon analysis will tell you that - or symbrklib for 
                     bcc,fcc,hcp).