:term:`GAUGE <GAUGE (CCRESPONSE)>`
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      Specifies the choice of representation of the electric dipole operator. Acceptable values are ``LENGTH`` for the usual length-gauge representation, ``VELOCITY`` for the modified velocity-gauge representation in which the static-limit optical rotation tensor is subtracted from the frequency- dependent tensor, or ``BOTH``. Note that, for optical rotation calculations, only the choices of ``VELOCITY`` or ``BOTH`` will yield origin-independent results.

      * **Type**: string
      * **Possible Values**: LENGTH, VELOCITY, BOTH
      * **Default**: LENGTH

