yuva: there are some quick answer... Relaxation: you can use FLAGS in atoms to relax/not relax in a particular Cartesian direction. example: Al 11.039040 5.580000 24.296861 0 0 1, means that Aluminium is fixed EXCEPT in the Z direction. So it will relax on Z direction. In your case I suggest to use this kind of relaxation for every atom with a fixed Constraint on bond lengths (see previous posts of mine).
KPoints: I, generally, use 'automatic' K points which is a kind of Monkhorst-Pack grid (more genereic). Suppose you have orthorhombic cell (a,b,c) where the magnitudes are (a=b < c), then I will use more Kpoints in a and b direction and less kpoints in c direction. Since Kpoints are defined in the reciprocal space (say, a'b'c' where magnitudes are a'b' > c'), you should use more k points to span the necessery irrep. areas in that reciproal space of a'b'c'. simply You can start with (see manual) K_POINTS automatic nx ny nz shiftx shifty shifty It is a good idea to visualize your supercell prior to put some values in nx,... By the way why you are using a BASH script? It was in QE package just to make tests quite smoothly/interactively. So pls use a simple *.in file which contains the input-data BETWEEN cat > alpen148.rx.in << EOF to EOF (bottom, near to Kpoints...) good luck Krishna Mohan GP Center for Superfunctional Materials POSTECH Sotuh Korea.
