Showing posts with label beads. Show all posts
Showing posts with label beads. Show all posts

10 June 2014

580. Python script: Interpolate between structures in a multi-xyz file

I'm doing a lot of NEB (nudged elastic band) calculations using nwchem at the moment, and while getting 'neb convergence' is simple enough, I often get an error along the lines of
3965547 @neb NEB calculation converged
3965548 @neb However NEB Gmax not converged...Try increasing the number of beads.

While that sounds simple enough it's nicer if you don't have to go back to the beginning and e.g. run a more fine-grained PES job to generate a reasonable trajectory (straight linear interpolation often doesn't work), then keep on running neb iterations. One way to cut down on time (presumably) is to simply pad the neb path xyz with intermediate structures, and that is what this python (2.7) script does.

Oh, and I really wish blogspot would support code inclusion better...

How to use:
python nebinterpolate.py -i neb_A_F.neb_final.xyz  -o test.xyz

Example:
Say we have the structure of methanol, and methanol in which the oxygen-carbon distance is 3.0 Ångström:

Here's the corresponding xyz file, which we'll call first.xyz:
6 C 0.03517 0.00549 0.03517 H -0.61778 -0.63407 0.66798 H 0.66798 -0.63407 -0.61778 H -0.60514 0.64647 -0.60514 O 0.83960 0.81877 0.83960 H 1.38912 0.20156 1.38912 6 C 0.03517 0.00549 0.03517 H -0.61778 -0.63407 0.66798 H 0.66798 -0.63407 -0.61778 H -0.60514 0.64647 -0.60514 O 1.76087 1.75017 1.76087 H 2.31039 1.13296 2.31039

Run nebinterpolate -i first.xyz -o second.xyz and you'll get a new xyz file with three structures -- the first one plus an intermediate structure:

Here's the new file, second.xyz:
6 C 0.03517 0.00549 0.03517 H -0.61778 -0.63407 0.66798 H 0.66798 -0.63407 -0.61778 H -0.60514 0.64647 -0.60514 O 0.83960 0.81877 0.83960 H 1.38912 0.20156 1.38912 6 structure 2 C 0.03517 0.00549 0.03517 H -0.61778 -0.63407 0.66798 H 0.66798 -0.63407 -0.61778 H -0.60514 0.64647 -0.60514 O 1.30024 1.28447 1.30024 H 1.84976 0.66726 1.84976 6 C 0.03517 0.00549 0.03517 H -0.61778 -0.63407 0.66798 H 0.66798 -0.63407 -0.61778 H -0.60514 0.64647 -0.60514 O 1.76087 1.75017 1.76087 H 2.31039 1.13296 2.31039

 Run it again, nebinterpolate -i second.xyz -o third.xyz, and you'll get:

Here's the new file, third.xyz:
6 C 0.03517 0.00549 0.03517 H -0.61778 -0.63407 0.66798 H 0.66798 -0.63407 -0.61778 H -0.60514 0.64647 -0.60514 O 0.83960 0.81877 0.83960 H 1.38912 0.20156 1.38912 6 structure 2 C 0.03517 0.00549 0.03517 H -0.61778 -0.63407 0.66798 H 0.66798 -0.63407 -0.61778 H -0.60514 0.64647 -0.60514 O 1.06992 1.05162 1.06992 H 1.61944 0.43441 1.61944 6 structure 2 C 0.03517 0.00549 0.03517 H -0.61778 -0.63407 0.66798 H 0.66798 -0.63407 -0.61778 H -0.60514 0.64647 -0.60514 O 1.30024 1.28447 1.30024 H 1.84976 0.66726 1.84976 6 structure 4 C 0.03517 0.00549 0.03517 H -0.61778 -0.63407 0.66798 H 0.66798 -0.63407 -0.61778 H -0.60514 0.64647 -0.60514 O 1.53056 1.51732 1.53056 H 2.08007 0.90011 2.08007 6 C 0.03517 0.00549 0.03517 H -0.61778 -0.63407 0.66798 H 0.66798 -0.63407 -0.61778 H -0.60514 0.64647 -0.60514 O 1.76087 1.75017 1.76087 H 2.31039 1.13296 2.31039

Now, the real use for this is when you've been optimising a string of structures using NEB and want to increase the number of images because you're not getting gmax convergence, or if you want to do a quick and rough optimisation and then get a prettier looking set of coordinates.

You can load the multi-xyz file in nwchem by using

NEB
   ...
  XYZ_PATH path.xyz
END


nebinterpolate.py 

#!/usr/bin/python

import sys

def getvars(arguments):
 switches={}

 version='0.1'
 
 try:
  if "-i" in arguments:
   switches['in_one']=arguments[arguments.index('-i')+1]
   print 'Input: %s '% (switches['in_one'])
  else:
   arguments="--help";
 except:
  arguments="--help";
  
 try:
  if "-o" in arguments:
   switches['o']=arguments[arguments.index('-o')+1].lower()
   print 'Output: %s'% switches['o']
  else:
   arguments="--help";
 except:
  arguments="--help";

 try:
  if "-w" in arguments:
   switches['w']=float(arguments[arguments.index('-w')+1])
   print 'Weighting: %i'% switches['w']
  else:
   print 'Assuming no weighting'
   switches['w']=1.0;
 except:
  switches['w']=1.0;

 doexit=0
 try:
  if ("-h" in arguments) or ("--help" in arguments):
   print '\t\t bytes2words version %s' % version
   print 'Creates interpolated structures'
   print 'from an multixyz file'
   print '--input \t-i\t multi-xyz file to morph'
   print '--output\t-o\t output file'
   print '--weight\t-w\t weight first structure vs second one (1=average; 0=start; 2=end)'
   print 'Exiting'
   doexit=1
 except:
  a=0 # do nothing
 if doexit==1:
  sys.exit(0)

 return switches

def getcmpds(switches):
 
 cmpds={}
 
 g=open(switches['in_one'],'r') 
 n=0
 xyz=[]
 atoms=[]
 structure_id=1

 for line in g:

  try:
   if len(xyz)==cmpds['atoms_'+str(structure_id)]:
    cmpds['coords_'+str(structure_id)]=xyz
    cmpds['elements_'+str(structure_id)]=atoms   
    structure_id+=2
    n=0
    atoms=[]
    xyz=[]
  except:
   pass

  n+=1
  line=line.rstrip('\n')
   
  if n==1:
   cmpds['atoms_'+str(structure_id)]=int(line)
  elif n==2:
   cmpds['title_'+str(structure_id)]=line
  else:
   line=line.split(' ')
   line=filter(None,line)
   xyz+=[[float(line[1]),float(line[2]),float(line[3])]]
   atoms+=[line[0].capitalize()]
 g.close

 cmpds['coords_'+str(structure_id)]=xyz
 cmpds['elements_'+str(structure_id)]=atoms   
 cmpds['w']=switches['w']
 cmpds['structures']=(structure_id)
 
 return cmpds

def morph(cmpds,structure_id):
 coords_one=cmpds['coords_'+str(structure_id)]
 coords_two=cmpds['coords_'+str(structure_id+2)]
 
 coords_morph=[]
 coords_diff=[]
 for n in range(0,cmpds['atoms_'+str(structure_id)]):
  morph_x=coords_one[n][0]+cmpds['w']*(coords_two[n][0]-coords_one[n][0])/2.0
  morph_y=coords_one[n][1]+cmpds['w']*(coords_two[n][1]-coords_one[n][1])/2.0
  morph_z=coords_one[n][2]+cmpds['w']*(coords_two[n][2]-coords_one[n][2])/2.0
  diff_x=coords_two[n][0]-coords_one[n][0]
  diff_y=coords_two[n][1]-coords_one[n][1]
  diff_z=coords_two[n][2]-coords_one[n][2]
  coords_morph+=[[morph_x,morph_y,morph_z]]
  coords_diff+=[[diff_x,diff_y,diff_z]]

 cmpds['atoms_'+str(structure_id+1)]=cmpds['atoms_'+str(structure_id)]
 cmpds['elements_'+str(structure_id+1)]=cmpds['elements_'+str(structure_id)]
 cmpds['title_'+str(structure_id+1)]='structure '+str(structure_id+1)
 cmpds['coords_'+str(structure_id+1)]=coords_morph

 return cmpds

def genxyzstring(coords,element):
 x_str='%10.5f'% coords[0]
 y_str='%10.5f'% coords[1]
 z_str='%10.5f'% coords[2]
 
 xyz_string=element+(3-len(element))*' '+10*' '+\
 (8-len(x_str))*' '+x_str+10*' '+(8-len(y_str))*' '+y_str+10*' '+(8-len(z_str))*' '+z_str+'\n'
 
 return xyz_string

def writemorph(cmpds,outfile):
 g=open(outfile,'w') 

 for m in range(1,cmpds['structures']+1):
  g.write(str(cmpds['atoms_'+str(m)])+'\n')
  g.write(str(cmpds['title_'+str(m)])+'\n')
  for n in range(0,cmpds['atoms_'+str(m)]):
   coords=cmpds['coords_'+str(m)][n]
   g.write(genxyzstring(coords, cmpds['elements_'+str(m)][n]))
 g.close

 return 0

if __name__=="__main__":
 arguments=sys.argv[1:len(sys.argv)]
 switches=getvars(arguments)
 cmpds=getcmpds(switches)

#check that the structures are compatible
 for n in range(1,cmpds['structures'],2):

  if cmpds['atoms_'+str(n)]!=cmpds['atoms_'+str(n+2)]:
   print 'The number of atoms differ. Exiting'
   sys.exit(1)
  elif cmpds['elements_'+str(n)]!=cmpds['elements_'+str(n+2)]:
   print 'The types of atoms differ. Exiting'
   sys.exit(1)
  cmpds=morph(cmpds,n)
 success=writemorph(cmpds,switches['o'])
 if success==0:
  print 'Conversion seems successful'