How to create the surface structure using the slab model (2D) of Chromium

We will create the surface structure using the slab (2D) model according to the information found in the following lecture on page 29.

http://susi.theochem.tuwien.ac.at/events/ws2006/WIEN2k-getting_started.pdf

We take the example of chromium as mentioned in the lecture.

The crystal structure in bulk structure is as follows:

Cr-Slab                                                                       
B   LATTICE,NONEQUIV.ATOMS:  1 229_Im-3m                                      
MODE OF CALC=RELA unit=ang                                                    
  5.461311  5.461311  5.461311 90.000000 90.000000 90.000000                  
ATOM   1: X=0.00000000 Y=0.00000000 Z=0.00000000
          MULT= 1          ISPLIT= 2
Cr         NPT=  781  R0=0.00005000 RMT=    2.3500   Z: 24.0                  
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
  48      NUMBER OF SYMMETRY OPERATIONS

To create the slab structure from the previous structure we take the example of the 001 plane.

We make supercell 1x1x3 P  with vaccum of 15 bohr in z direction

 Filename of original struct file:

Number of cells in x direction:
Number of cells in y direction:
Number of cells in z direction: 3

Optional shift of all atoms (fractional coordinates)
in x direction:
in y direction:
in z direction:
Enter your target lattice type: P

(Some choices are restricted by symmetry)
For surfaces or isolated molecules: (for P lattice only)
Vacuum in x-direction [bohr]:
Repeat atoms at x=0:
Vacuum in y-direction [bohr]:
Repeat atoms at y=0: Vacuum in z-direction [bohr]: 15
Repeat atoms at z=0:Y

you will get the following structure

Cr-Slab                                                                        
P   LATTICE,NONEQUIV. ATOMS  7    
MODE OF CALC=RELA unit=ang
  5.461311  5.461311 31.383933 90.000000 90.000000 90.000000
ATOM   1: X=0.00000000 Y=0.00000000 Z=0.00000000
          MULT= 1          ISPLIT= 8
Cr         NPT=  781  R0=0.00005000 RMT=    2.3500   Z: 24.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
ATOM   2: X=0.00000000 Y=0.00000000 Z=0.17401614
          MULT= 1          ISPLIT= 8
Cr         NPT=  781  R0=0.00005000 RMT=    2.3500   Z: 24.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
ATOM   3: X=0.00000000 Y=0.00000000 Z=0.34803229
          MULT= 1          ISPLIT= 8
Cr         NPT=  781  R0=0.00005000 RMT=    2.3500   Z: 24.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
ATOM   4: X=0.00000000 Y=0.00000000 Z=0.52204843
          MULT= 1          ISPLIT= 8
Cr         NPT=  781  R0=0.00005000 RMT=    2.3500   Z: 24.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
ATOM   5: X=0.50000000 Y=0.50000000 Z=0.08700807
          MULT= 1          ISPLIT= 8
Cr         NPT=  781  R0=0.00005000 RMT=    2.3500   Z: 24.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
ATOM   6: X=0.50000000 Y=0.50000000 Z=0.26102422
          MULT= 1          ISPLIT= 8
Cr         NPT=  781  R0=0.00005000 RMT=    2.3500   Z: 24.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
ATOM   7: X=0.50000000 Y=0.50000000 Z=0.43504036
          MULT= 1          ISPLIT= 8
Cr         NPT=  781  R0=0.00005000 RMT=    2.3500   Z: 24.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
   0      NUMBER OF SYMMETRY OPERATIONS

If we run sgroup we will get the following structure

Cr-Slab                                                                        
P   LATTICE,NONEQUIV.ATOMS:  4 123 P4/mmm
MODE OF CALC=RELA unit=ang
  5.461311  5.461311 31.383933 90.000000 90.000000 90.000000
ATOM   1: X=0.50000000 Y=0.50000000 Z=0.23897578
          MULT= 2          ISPLIT= 8
       1: X=0.50000000 Y=0.50000000 Z=0.76102422
Cr1        NPT=  781  R0=0.00005000 RMT=    2.3500   Z: 24.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
ATOM   2: X=0.50000000 Y=0.50000000 Z=0.58700807
          MULT= 2          ISPLIT= 8
       2: X=0.50000000 Y=0.50000000 Z=0.41299193
Cr2        NPT=  781  R0=0.00005000 RMT=    2.3500   Z: 24.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
ATOM   3: X=0.00000000 Y=0.00000000 Z=0.32598385
          MULT= 2          ISPLIT= 8
       3: X=0.00000000 Y=0.00000000 Z=0.67401615
Cr3        NPT=  781  R0=0.00005000 RMT=    2.3500   Z: 24.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
ATOM   4: X=0.00000000 Y=0.00000000 Z=0.50000000
          MULT= 1          ISPLIT= 8
Cr4        NPT=  781  R0=0.00005000 RMT=    2.3500   Z: 24.0
LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
                     0.0000000 1.0000000 0.0000000
                     0.0000000 0.0000000 1.0000000
  16      NUMBER OF SYMMETRY OPERATIONS

You can see more information for another compound on this video

Good Luck