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[Quan Phung Manh <manhquank9@gmail.com>]

I'm learning CO on TiO2 surface using Molecular dynamics. This is the input file

#Definition of the k-point grids
kptopt 1          
nshiftk 2
shiftk  0.5 0.0 0.0  
        0.0 0.5 0.0
ngkpt  2 2 1

#Definition of the unit cell
acell 5.5045254737E+00  1.2085958617E+01  3.9054040855E+01

#Definition of the atom types
ntypat 5          
znucl 22 8 1 6 8   
 
#Definition of the atoms
natom 27          
typat 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 4 5       
xangst
0.000000000     3.433979661     1.702548614
0.000000000    -0.030909893     4.965652343
0.000000000     3.183736244     8.301964739
0.000000000    -0.007453315    11.238648984
1.456434713     0.249962141     1.826819536
1.456434713     3.160658047     4.997001953
1.456434713    -0.015133698     8.106539672
1.456434713     3.191007391    11.602913960
0.000000000     3.134088248     3.712077931
0.000000000    -0.036979110     6.917159950
0.000000000     3.187105620    10.148049014
0.000000000     0.085095967     3.023282974
0.000000000     3.185355376     6.258969546
0.000000000    -0.016913131     9.441795449
0.000000000     3.189623132    12.679519266
1.456434713     4.628213937     1.641901518
1.456434713     1.210599710     5.011844303
1.456434713     4.461364915     8.201911335
1.456434713     1.198244350    11.547258895
1.456434713     2.045849552     1.627326844
1.456434713     5.122602774     4.938437347
1.456434713     1.894988115     8.197087652
1.456434713     5.182999613    11.552484499
0.000000000     3.197805952     0.000000000
2.912869425     0.000000000     0.700956091
0.000000000    -0.007453315    13.738648984
0.000000000    -0.007453315    14.866648984

natfix 25
iatfix 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

#Definition of the planewave basis set
ecut  40.0         

#Definition of the SCF procedure
nstep 200              # Maximal number of SCF cycles
tolmxf  5.0d-4         
toldff  5.0d-5         

#Optimization of the lattice parameters
ionmov  9              # Langevin molecular dynamics
ntime  20
mditemp 100    
iprcel 45

occopt 3
tsmear 9.5d-5 

And I have many warnings in MOLDYN STEP NUMBER    1. For example
 symatm : WARNING -
  Trouble finding symmetrically equivalent atoms
  Applying inv of symm number  2 to atom number   1  of typat  1
  gives tratom= -1.0111E-03  5.3775E-01  8.2374E-02.
  This is further away from every atom in crystal than the allowed tolerance.
  The inverse symmetry matrix is -1  0  0
                                  0  1  0
                                  0  0  1
  and the nonsymmorphic transl. tnons =    0.0000000    0.0000000    0.0000000
  The nearest coordinate differs by -2.022E-03  0.000E+00  0.000E+00
  for indsym(nearest atom)=    1

  This indicates that when symatm attempts to find atoms symmetrically
  related to a given atom, the nearest candidate is further away than some
  tolerance.  Should check atomic coordinates and symmetry group input data.

and an error
 symatm : ERROR -
  Largest error (above) is so large that either input  atomic coordinates (xred)
  are wrong or space group symmetry data is wrong.
  Action : correct your input file.

 leave_new : decision taken to exit ...

I choose ionmov = 1 and have no error.

Is there anything wrong with the input file?

Best regards
-- 
Quan Phung Manh
Khoa Hoá học - ĐH Khoa học tự nhiên - 19 Lê Thánh Tông Hà Nội
ĐT: 01663 922 302