# Adding external electric field in ORCA with specific strength

Can anybody share methods to apply an external Electric field in ORCA? thanks!

## 1 Answer

From the ORCA forum thread:

Actually there is an undocumented feature for this purpose:

%scf
efield X-field-strength-in-a.u. , Y-field-strength-in-a.u. , Z-field-strength-in-a.u.
end


I have used it to compare dipole moments obtained via numeric and analytic differentiation and it worked fine. But do be careful as undocumented features do not officially exist (although in this case it might have just been overlooked in the manual)

I searched the manual, but didn't find any mention about how to add it.