Chapter 29. Directives controlling the choice of the probe

There are two different methods of choosing your Probe or Probes:

1. The properties of the Probe may be selected by entering the Probe's Symbol. This is the recommended method, and it is only necessary to enter the Symbol for the Probe somewhere before IEND in the list of Control Directives. Thus for a phenolic hydroxyl Probe you would simply enter: OH on a line by itself somewhere before IEND. When you use directive POSI (in order to define explicit grid points at which you want the GRID energy to be calculated), you may enter the names of several different Probes one after the other in the list of Control Directives thus:

   POSI 1.23 27.86 1. Note that the input on POSI 45.9 1.1 117.03 each line is free-format, POSI 0.9 -1. 67. so do not use Tabs to OH format the lines. Note O1 also that POSI and the O Probe Symbols must be OES entered before the line OC2 with: IEND

   The Grid energy will then be computed at each point for each Probe. The maximum number of Probes is defined by Parameter MAXPRO and the maximum number of grid points by MAXPOS. The list may not include multi-atom Probes. Similarly, if you are studying several Targets one after the other as a Set, you may enter several Probe Symbols in the list of Directives.

2. The properties of a Probe may be defined one by one, as described in Section 31.3 for the Probe. This is a very flexible method of input for a single-atom Probe. The Energy Variables are its Van der Waals Radius, Polarisability, Charge etc. They are described in detail below.

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AR.CONHR 
CIS 
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IEND 
Title of the job