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Subsections
8.2 averd
8.2.1 Description
Averd computes average densities and corresponding
natural molecular orbitals. Given a set of density
matrices in the same basis set, an average density matrix is
constructed and diagonalized to give average natural orbitals.
These orbitals have noninteger occupation numbers, although they
usually are fairly well clustered in one strongly occupied
part and one weakly occupied part. From basic mathematical
properties of natural orbitals, a truncated set of the orbitals
constructed this way constitutes the most compact basis of
oneelectron functions of that given size. In other words, the smallest
set of functions to span the average space within a certain
accuracy has been obtained. Averd
is in essence very similar to Genano.
8.2.2 Dependencies
Averd needs a set of input densities. Any of the
programs, which generate a density must preceed.
8.2.3 Files
Below is a list of the files that are used/created by
Averd.
File  Contents

RUNFILE  File for communication of auxiliary information generated by the program
SEWARD.

ONEINT  File with oneelectron integrals generated by SEWARD.

RUN***  A set of RunFiles on which a density matrix is stored. This density
matrix is read and added to the average. If ORBItals is
given, these files are not needed.

NAT***  A set of orbitals in the format generated by SCF or
RASSCF. The orbitals are used to generate a density matrix,
which is added to the average. Only required if ORBItals is
given.

File  Contents

AVEORB  The average orbitals generated by Averd. They are stored in
the same way as SCForbitals and can be used as INPORB.

8.2.4 Input
Keyword  Meaning

TITLe  Title of the calculation.

WSET  Followed by two rows. On the first the number of input orbitals are
given, N. Second row contains N numbers each giving a weight
for the k^{th} input density matrix to the average density. The
weights are normalized by Averd, hence only the
ratio of the numbers have any significance. This keyword
is mandatory.

PRINt  Print level. 1 is default. Higher than 3 is not recommended for the
average user.

ORBItals  This keyword signifies that the densities should be created from
average orbitals in the files NAT***, not directly from the density
matrices on the files RUN***. The default is to use the density
matrices on RUN***.

OCCUpation  Followed by one number. The number of average orbitals with an
occupation higher than this number is reported for each symmetry.
Since the occupation is the guide for how to truncate the orbitals
in subsequent applications, this is an easy way to get hold of
that number. The default is 10^{5}.

In this example, two density matrices are averaged and their
average orbitals are computed.
&Seward
Basis set
O.anos.Pierloot.10s6p3d.7s4p2d.
O 0.0000 0.0000 0.3000
End of Basis set
Basis set
H.anos.Pierloot.7s3p.4s1p.
H1 0.0000 1.4300 0.8070
H2 0.0000 1.4300 0.8070
End of Basis Set
&FfPt
Dipo
z 0.005
End of Input
&Scf
Occupation
5
>>COPY $Project.RunFile RUN001
&FfPt
Dipo
z 0.005
&Scf
Occupation
5
End of Input
>>COPY $Project.RunFile RUN002
&Averd &End
Wset
2
1.0 1.0
Occupation
1d6
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Previous: 8.1 alaska


