Estimation of XPS core level electron binding energies

12

Hi there,

if you want to calculate core electron binding energies of organic molecules, you may want to check my PSI4 plugin https://github.com/Masterluke87/psixas. Though it is more written to calculate NEXAFS spectra (using TP-DFT), you can use it to calculate XPS positions as well. For example, the 1s CEBE of water can be obtained by using:

import psixas

molecule {
O 0.27681793323501 0.00000014791107 0.00000000000000
H 0.86159097690242 0.76505117501585 0.00000000000000
H 0.86159108986257 -0.76505132292693 0.00000000000000
symmetry c1
}

set {
basis def2-TZVP
}

set scf {
reference uks
scf_type MEM_DF
}

set psixas {
print 1
prefix WATER
MODE GS+EX
ORBS [0 ]
OCCS [0.0]
SPIN [b ]
DAMP 0.2
OVL [T]
FREEZE [T]
}
energy(‘psixas’,functional=‘PBE’)

Then:

grep “FINAL” output.dat
FINAL GS SCF ENERGY: -76.37667773 [Ha]
FINAL EX SCF ENERGY: -56.56555074 [Ha]

And you can calculate the XPS position, which is in this case 539.08 eV. Hope that helps!

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