Field strength



Hi, everyone!
 when one does calculations of static electric field with most quantum
 chemistry codes (like Gaussian, GAMESS, DMol3), he/she needs to input
 the field strength in atomic unit. As I know, the atomic unit of the
 field strength can be converted to "eV/A". However, I found from
 papers
 (and physical text books) that  the unit of "V/A" is used for the
 field
 strength.  Can someone explain the difference between the two "field
 strength"?
 Thanks!
 Frank