# CounterpoiseCounterpoise
corrections [433,434]
may be computed using the **Counterpoise** keyword, which can be used on an
energy calculation, optimization or frequency calculation or BOMD. The **Counterpoise**
keyword takes an integer value specifying the number of fragments or monomers
in the molecular structure. The facility also requires an additional integer to
be placed at the end of each atom specification indicating which fragment/monomer
it is part of. **NewGhost**
Requests new-style ghost atoms for which integration grid points for DFT quadrature
are included. **NewBq** is a synonym for **NewGhost**. This is the default
and the recommended method.
**OldGhost** Requests old-style ghost
atoms. **OldBq** is a synonym for **OldGhost**. This option is only useful
for comparison with previous results.
**Counterpoise
Input. **Here are examples using a Z-matrix (left) and Cartesian coordinates
(right):
# MP2/6-31G Counterpoise=2 Opt # MP2/6-31G Counterpoise=2 Opt
Counterpoise with Z-matrix Counterpoise with Cartesian
0,1,0,3,1,2 0,1
O,0.0,0.0,0.0,1 *structures begin here* 1 0.00 0.00 0.92 1
O,1,ROO,2 9 0.17 0.00 2.73 2
X,1,1.,2,X3O 1 0.77 0.00 3.43 2
H,1,RO1H,3,HOX3,2,90.,0,1 9 0.00 0.00 0.00 1
H,1,RO1H,3,HOX3,2,-90.,0,1
X,2,1.,1,52.5,3,180.,0
H,2,RO2H1,6,H7OX,1,180.,0,2
H,2,RO2H2,6,H8OX,1,0.,0,2
Z-matrix variables...
Note that the Z-matrix input requires a **0** after
the dihedral angle value/variable (to indicate that the final angle is a dihedral)
prior to the fragment number. Also, the first atom in the Z-matrix must be given
in Cartesian coordinates. Clearly, using Cartesian coordinates for such jobs makes
specifying fragment numbers in the input much more straightforward. The
preceding Z-matrix also illustrates the use of fragment-specific charge and spin
multiplicity specifications. The format of the corresponding input line in this
case is: *total-charge, total-spin, frag. 1-charge, frag.1 multiplicity,
frag. 2 charge, frag. 2 multiplicity *
An example counterpoise optimization
using ECPs:
# hf/lanl2dz counterpoise=2 nosymm opt test
HBr + HF, optimization with counterpoise correction using ECP basis
0 1
H -0.046866 0. 0.586860 1
Br -0.331864 0. -0.801000 1
F 0.396755 0. 2.739275 2
H 0.584835 0. 3.641534 2
**Counterpoise Output.** Here is some sample output from a **Counterpoise**
calculation:
Counterpoise: corrected energy = -2660.083831739527
Counterpoise: BSSE energy = 0.003902746890
These lines give the corrected energy and
basis set superposition errors, respectively. |