How to create a nanowire structure using StructGen

Pocedure of our colleague Dr D. P. Rai

                         Department of Physics, Pachhunga University College, Aizawl, 796001,India

The model of monatomic Fe-nanowire is formed by the supercell method in which the position of Fe atom is taken as(0.5, 0.5, 0.5) and the vacuum of 10 ̊A is applied along x-axis and y-axis in order to discontinue the atomic wave functionand to break the crystal symmetry along x and y direction. As a result of this the repetition of the atom takes place only in one direction i.e. along the z-axis. The structure thus obtained is 1D Fe atomic chain (periodic linear chain of identical atoms with a single atom per unit cell) with the repetition along z-axis as shown in Fig.1a. The lattice constant (a and b) of the Fe-wire has been changed to a=b=10 ̊A. The lattice constant (c) was optimized and the plot of energy ver-sus c is shown in Fig.1a(top). The optimized lattice constant(c) of Fe-wire is 2.38 ̊A.

1- Creation of the struct file  (the starting structure )

Title: 

Lattice: Type: B

Spacegroups from Bilbao Cryst Server

Lattice parameters in
       a= b= c=
       α= β= γ=

Inequivalent Atoms: 1
Atom 1: Z= RMT=
       Pos 1: x= y= z=

Number of symmetry operations: generate

View only mode -->edit STRUCT file

- X supercell 1x1x9   ( to create the nanowire structure)

Filename of original struct file:
Number of cells in x direction:
Number of cells in y direction:
Number of cells in z direction: 9

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

(Some choices are restricted by symmetry)
For surfaces or isolated molecules: (for P lattice only)
Vacuum in x-direction [bohr]: 10
Repeat atoms at x=0:
Vacuum in y-direction [bohr]: 10
Repeat atoms at y=0: Vacuum in z-direction [bohr]:
Repeat atoms at z=0:Y

The new tructure 

View only mode -->edit STRUCT file

Title: 

Lattice: Type: P

Spacegroups from Bilbao Cryst Server

Lattice parameters in

       a= b= c=

       α= β= γ=

Inequivalent Atoms: 18

Atom 1: Z= RMT=

       Pos 1: x= y= z=

Atom 2: Z= RMT=

       Pos 1: x= y= z=

Atom 3: Z= RMT=

       Pos 1: x= y= z=

Atom 4: Z= RMT=

       Pos 1: x= y= z=

Atom 5: Z= RMT=

       Pos 1: x= y= z=

Atom 6: Z= RMT=

       Pos 1: x= y= z=

Atom 7: Z= RMT=

       Pos 1: x= y= z=

Atom 8: Z= RMT=

       Pos 1: x= y= z=

Atom 9: Z= RMT=

       Pos 1: x= y= z=

Atom 10: Z= RMT=

       Pos 1: x= y= z=

Atom 11: Z= RMT=

       Pos 1: x= y= z=

Atom 12: Z= RMT=

       Pos 1: x= y= z=

Atom 13: Z= RMT=

       Pos 1: x= y= z=

Atom 14: Z= RMT=

       Pos 1: x= y= z=

Atom 15: Z= RMT=

       Pos 1: x= y= z=

Atom 16: Z= RMT=

       Pos 1: x= y= z=

Atom 17: Z= RMT=

       Pos 1: x= y= z=

Atom 18: Z= RMT=

       Pos 1: x= y= z=

Number of symmetry operations: generate

View only mode -->edit STRUCT file

Because the big values o a an b paraeters, there is not any correlation or exchange interaction between atoms in these 2 directions, so it will looks like this

 - X sgroup (this step is not necessary, it's just to small unit cell)

Title: 

Lattice: Spacegroup: 63_Cmcm

Splitting of equivalent positions not available. To split you must select a lattice type

Spacegroups from Bilbao Cryst Server

Lattice parameters in
       a= b= c=
       α= β= γ=

Inequivalent Atoms: 1
Atom 1: Z= RMT=
       Pos 1: x= y= z=
       Pos 2: x= y= z=

Number of symmetry operations:

View only mode -->edit STRUCT file