Output Precision in OUTCAR/OSZICAR
Posted: Thu May 04, 2023 8:17 pm
Is there a INCAR tag I can use to get the full precision of the total energy and other output quantities instead of the standard 8 digits after the decimal in VASP 6?
unfortunately there is no precision tag. You would have to change the source code.
Depending on the chosen algorithm, there are several files to edit. For instance following lines in electron.F
can be changed to print more than 8 significant digits (this starts at line 890 in vasp-6.4.1):
Code: Select all
7240 FORMAT(/ &
' Free energy of the ion-electron system (eV)'/ &
& ' ---------------------------------------------------'/ &
& ' alpha Z PSCENC = ',F18.8/ &
& ' Ewald energy TEWEN = ',F18.8/ &
& ' -Hartree energ DENC = ',F18.8/ &
& ' -exchange EXHF = ',F18.8/ &
& ' -V(xc)+E(xc) XCENC = ',F18.8/ &
& ' PAW double counting = ',2F18.8/ &
& ' entropy T*S EENTRO = ',F18.8/ &
& ' eigenvalues EBANDS = ',F18.8/ &
& ' atomic energy EATOM = ',F18.8/ &
& ' Solvation Ediel_sol = ',F18.8/ &
& ' ---------------------------------------------------'/ &
& ' free energy TOTEN = ',F18.8,' eV'// &
& ' energy without entropy =',F18.8, &
& ' energy(sigma->0) =',F18.8)
...
Bear in mind though, vasp does calculations in double precision with 10 significant digits.
Rounding errors from floating point operations become significant beyond the 9th digit.