PROPERTY [property name] [CENTER ((com || coc || origin || arb <real x y z>) default coc)] [VECTORS ...] END
Calculation of properties is accomplished with TASK PROPERTY
after the completion of an energy (or MP2 gradient) calculation. The
following properties can be computed for all wavefunctions that produce
orbitals, including Hartree-Fock (closed-shell RHF, open-shell ROHF, and
open-shell UHF), DFT (closed-shell and open-shell spin unrestricted),
MCSCF (complete active space), and MP2 (closed-shell RHF and open-shell
UHF).
The default molecular orbital file $file_prefix$.movecs
is used
unless a vectors directive (Section 10.5) is provided. It is
therefore only necessary to include a vectors directive if the MO vectors
to be analyzed are not coming from the default file, e.g., if they have
been previously redirected, or if MP2 natural orbitals (file extension
".mp2nos"
) are being anaylzed. The MP2 natural orbitals MUST be
used if the user wants MP2 properties.
Note that presenting any property input causes all previous property input to be ``forgotten'', unlike other NWChem modules.
Each property can be requested by means of a subdirective among the subdirectives provided :
The ``all'' keyword generates all currently available properties.
The request to NBOFILE does not execute the Natural Bond Analysis code, but simply creates an input file to be used as input to the stand-alone NBO code. To execute the NBO analysis directly, see Section 33.1. All other properties are calculated upon request.
An additional subdirective is provided to specify the origin of the molecular orbitals used in the calculation of the molecular properties. This is the 'vectors' subdirective, also used in the SCF and DFT tasks. For a full description of this subdirective the user is refered to the description found in the SCF description. By default, the input file used for the calculation of the properties has the .movecs name extension.
The user also has the option to choose the center of expansion for the dipole, quadrupole, and octupole calculations.
[CENTER ((com || coc || origin || arb <real x y z>) default coc)]
com is the center of mass, coc is the center of charge, origin is (0.0, 0.0, 0.0) and arb is any arbitrary point which must be accompanied by the coordinated to be used. Currently the x, y, and z coordinates must be given in the same units as UNITS in GEOMETRY (See Section 6.1).
Following the successful completion of an electronic structure
calculation, a Natural Bond Orbital (NBO) analysis may be carried out
in the following way. On restart specify the TASK as PROPERTY and
supply the sub-directive NBOFILE to the PROPERTY directive. NWChem
will query the rtdb and construct an ASCII file,
<file_prefix>.gen
, that may be used as input to the stand alone
version of the NBO program, gennbo. <file_prefix>
is equal to
string following the RESTART directive. The input deck may be edited
to provide additional options to the NBO calculation, (see the NBO
user's manual for details.) The other option in to directly run the NBO
analysis (See Section 33.1 for more information).