Swap out some of the atoms from the core with the atoms from the shell:

• Copy the "pdpt/" directory into the "VASPMod0/" directory and re-name the directory to "ptpd".
• Using vim, edit your POSCAR to swap out some of the atoms from the core with the atoms from the shell. Remember, the first 6 atom positions are Pd and the last 32 are Pt, so swaping the first position line and the 7th position line swill make atom 0th atom (Pd) a Pt atom and the 7th atom (originally Pt) a Pd atom. By simply moving some of the first 32 lines to the end of the list of atoms, you will have swapped some core and shell atoms. For the sake of calculating the segregation energy, you should only swap one pair of Pd and Pt atoms.
• After editing the POSCAR, make sure to run sortpos.py to make sure that the elements are alphabetically ordered
• Then run sogetsoftpbe.py to get the correct POTCAR for your POSCAR.
• Use ag to verify that some of the core atoms have been swapped with the shell atoms.
• Remember to change the job name in the submit file.
• Run this job and calculate the new cohesive energy.