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Orca (Read 7039 times)
Gerrit-Jan Linker
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Orca
27.09.13 at 13:36:09
 
Orca
 
ORCA is a flexible, efficient and easy-to-use general purpose tool for quantum chemistry with specific emphasis on spectroscopic properties of open-shell molecules.
 
Orca homepage: http://cec.mpg.de/forum/
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Gerrit-Jan Linker
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Re: Orca
Reply #1 - 27.09.13 at 13:57:01
 
Test calculation with Orca
 

#!/b
in/bash
 
Project="CO"; export $Project
 
cd $TMPDIR
 
cat<<EOF>$Project.input
%coords
 CTyp xyz
 Charge 0
 Mult 1
 Units Angs
 coords
   C 0.0 0.0 0.0
   O 0.0 0.0 1.2
 end
end
EOF
 
cat $Project.input > $PBS_O_WORKDIR/$Project.output
 
orca $Project.input &>> $PBS_O_WORKDIR/$Project.output

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« Last Edit: 27.09.13 at 13:57:43 by Gerrit-Jan Linker »  

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Orca: basis set
Reply #2 - 06.10.13 at 22:12:48
 
Orca: basis set
 
To define a basis set in an ORCA calculation the basis block needs to be added to the input. For example:
 
Minimal basis:
%basis  
  basis STO_3G
 end
 
6-31G** basis:
%basis  
  basis _6_31G
  pol    _dp
 end
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« Last Edit: 12.10.13 at 12:15:17 by Gerrit-Jan Linker »  

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Orca: UHF
Reply #3 - 12.10.13 at 18:44:34
 
Orca: UHF
 
An UHF calculation is done in Oracle by starting the input file with this line (also specifies tight SCF criteria):
! uhf TightSCF
...
followed by the coords and basis blocks
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Orca: Broken Symmetry
Reply #4 - 13.10.13 at 16:01:50
 
Orca: Broken Symmetry
 
In Orca a spin-symmetry broken solution can be obtained using the following keywords in the SCF block:
 
%scf  BrokenSym  NA,NB
end
 
NA= number alpha electrons
NB= number of beta electrons
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Orca: Restart from saved vectors
Reply #5 - 21.10.13 at 17:11:09
 
Orca: Restart from saved vectors
 
To start a calculation from vectors obtained from another calculation, the %moinp input needs to be given.
 
%moinp "CO.gbw"
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Orca: DIIS
Reply #6 - 24.10.13 at 09:04:32
 
Orca: DIIS
 
 
%scf
#  control  of  the  DIIS  procedure
CNVDIIS         true    #  default:  true
DIISStart     0.1     #  default:  0.2
DIISMaxIt     5         #  default:  12
DIISMaxEq     7         #  default:  5
DIISBFac       1.2     #  default:  1.05
DIISMaxC       15.0    #  default:  10.0
end
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« Last Edit: 24.10.13 at 21:03:44 by Gerrit-Jan Linker »  

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Orca: Orbital Localisation
Reply #7 - 03.11.13 at 21:19:48
 
Orca: Orbital Localisation
 
Orbitals can be localised by using the %loc section in the input. In the manual the following example can be found:
 
%loc
LocMet    PipekMezey  #  localization  method.  Choices:
#  PipekMezey  (=PM)
#  FosterBoys  (=FB)
T_Core    -1000  #  cutoff  for  core  orbitals
Tol         1e-8    #  conv.  Tolerance  (default=1e-6)
MaxIter  20       #  max.  no  of  iterations  (def.  128)
end
 
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