# CFOUR_DERIV_LEVEL

> Specifies whether or not energy derivatives are to be calculated and if so whether first or second derivatives are computed. ZERO (= 0) derivatives are not calculated, FIRST (=1) first derivatives are calculated, SECOND (=2) second derivatives are calculated. Note that this keyword usually needs not be set in any calculation since it is automatically set if the appropriate other options in the CFOUR namelist are turned on. PSI4 Interface: Keyword set from type of computation command: ZERO if `energy()`, FIRST if `gradient()` or `optimization()`, etc.

> - Type: string
> - Possible Values: ZERO, FIRST, SECOND
> - Default: ZERO