Q-Chem 4.3 User’s Manual

3.14 Addition of External Charges ($external_charges)

If the $external_charges keyword is present, Q-Chem scans for a set of external charges to be incorporated into a calculation. The format for a set of external charges is the Cartesian coordinates, followed by the charge size, one charge per line. Charges are in atomic units, and coordinates are in angstroms (unless atomic units are specifically selected, see INPUT_BOHR). The external charges are rotated with the molecule into the standard nuclear orientation.

Example 3.16  General format for incorporating a set of external charges.

   x-coord1  y-coord1  z-coord1  charge1
   x-coord2  y-coord2  z-coord2  charge2
   x-coord3  y-coord3  z-coord3  charge3

In addition, the user can request to add a charged cage around the molecule by using ADD_CHARGED_CAGE keyword The cage parameters are controlled by CAGE_RADIUS, CAGE_POINTS, and CAGE_CHARGE. More details are given in Section 6.7.6.