##master-page:HelpTemplate
##master-date:Unknown-Date
#format wiki
#language en
#Please change following line to BDF module name

= MCSCF =
<<TableOfContents(4)>>

{{{
Multi-configurational self consistent field program.
}}}
== General keywords ==
=== Core ===
{{{#!wiki
  Number of frozen internal orbitals in each irreps.
}}}
Example:

=== Delete ===
{{{#!wiki
  Number of frozen external orbitals in each irreps.
}}}
Example:


=== Close ===
{{{#!wiki
  Number of inactive orbitals in each irreps.
}}}
Example:


=== Active ===
{{{#!wiki
  Number of active orbitals in each irreps.
}}}
Example:

=== actel ===
{{{#!wiki
  Number of active electrons in active space.
}}}
Example:

=== RootPrt ===
{{{#!wiki
  Print the target state (root) energy for calculating numerical gradient of this state in numgrad module, default is 1.
}}}
Example:
{{{
RootPrt
 3   # the third state (root) energies will be printed.
}}}

=== Symmetry ===
{{{#!wiki
  Symmetry of the target state.
}}}
Example:

=== Spin ===
{{{#!wiki
  Spin multiplicity. 2S+1
}}}
Example 1:
{{{
Spin
 1   # singlet
}}}

Example 2:
{{{
Spin
 2  # doublet
}}}


=== Roots ===
{{{#!wiki
Three or one lines should be provided.

Line 1: Two or three integrals. The first one is the number of averaged states and the second one is the number of states calculated in CI. If the third number is one, the lowest states will be averaged with the same weights; if it is zero or missing, two additional lines should be provided.

Line 2: which states should be averaged

Line 3: weight of states in state-average calcualtion
}}}

Example:
{{{
Roots
3  4     # 3 states will be averged, 4 states will be calculated
1 2 3   # States 1 2 3 will be averged
1 1 1    # equal weight for each state
}}}
This is equivalent to
{{{
Roots
3  4  1   # The first 3 states will be averged with the same weights & 4 states will be calculated
}}}

=== Ras ===
{{{#!wiki
several lines should be provided for controlling RASSCF calculations.
Line 1: number for different RAS spaces, like RAS1, RAS2, RAS3, ...., the index for CAS space which all electron excitations are allowed.
Line 2: allowed excitation electron number of the double occupied RAS spaces or all electrons of CAS or allowed accept electrons of unoccupied RAS space. 
From Line 3 to Line (RAS spaces number plus 2) set active orbital with symmetry of these RAS spaces.
}}}
Example:
{{{
ras
2 2  ! there are two RAS spaces, the second RAS space is CAS space.
2 6  ! first RAS space (RAS1) allows maximum 2 electrons are excited. second RAS space (RAS2) allow all of 6 electrons are excited. 
5 0 0 3  ! active orbitals of each irreps of RAS1
0 2 3 1  ! active orbitals of each irreps of RAS2.
}}}
Comment:
{{{
   With keyword 'RAS' setting, keywords 'active' is useless and can be missing.
}}}



=== MixCI ===
{{{#!wiki
Four lines should be provided for controlling state average CASSCF calculations with different spin and space symmetries of CAS-CI.
Line 1: number for different types of CI.
Line 2: spin multiplicity for each type of CI.
Line 3: averaged state number for each type of CI.
Line 4: irreducible representation number for each type of CI.
}}}
Example:
{{{
MixCI
  3      # number for three types of CI.
1 3 5    # singlet, triplet and quintet for three types of CI, respectively.
3 1 2    # three, one and two averaged states for three types of CI, respectively, sum of them must be equal to that setting in 'Nroots'.
1 4 3    # first, fourth, third irreducible representation for three types of CI, respectively.
}}}
Comment:
{{{
   With keyword 'MixCI' setting, keywords 'spin' and 'symmetry' are useless and can be missing.
}}}

=== Guess ===
{{{#!wiki
  Initial molecular orbitals reading.
}}}

Notice:
{{{
  Guess : hforb  is default with SCF MOs as initial MOs from TMPDIR by the unformatted File hforb.
  Guess : mcorb  is set with recent MCSCF MOs as initial MOs from TMPDIR by the unformatted File mcorb.
  Guess : inporb is set with recent MCSCF MOs as initial MOs from WORKDIR by the formatted File inporb, canorb, scforb in turn.
  Guess : hcore  is set with Nuclear core Hamiltonian as initial MOs.
  Guess : huckel is set with Extend Huckel Hamiltonian as initial MOs.
}}}


Example 1:
{{{
Guess
 hforb   # read SCF MOs from scratch file, which is default.
}}}

Example 2:
{{{
Guess
 hcore   # with Nuclear core Hamiltonian as initial MOs.
}}}

Example 3:
{{{
Guess
 inporb   # read from local files '$Project.inporb', '$Project.canorb', and '$Project.scforb' in turn to find guess MOs.
}}}

Example 4:
{{{
Guess
 mcorb   # read CASSCF MOs from scratch file.
}}}

=== Direct ===
{{{#!wiki
  MCSCF calculation with one direct CI step in each micro-iteraction, which may be useful in large CI system, 
  default is without this keyword.
}}}

=== Molden ===
{{{#!wiki
  Output MCSCF orbital into Molden format file.
}}}

=== iprtmo ===
{{{#!wiki
  Require to print MO coefficients.
  Values: 1 Only print orbital energy and occupation numbers. 2 Print all information.
}}}

=== CIonly ===
{{{#!wiki
  Only CI optimization is done, default is without this keyword.
}}}

=== CIread ===
{{{#!wiki
  Use previous CI vector as initial on each CI calculation except for the first CI calculation. Default is not read.
}}}


=== Quasi ===
{{{#!wiki
  Use Quasi-Newton method for orbital optimization, like Second-Order SCF method, which requires less Memory and has fast MO integral Transformation than Second-Order method, like Newton-Raphson method.
}}}

=== Werner ===
{{{#!wiki
  Use Second-Order method for orbital optimization by Werner nonlinear optimization, This is default.
}}}
Commit:
{{{Notice: please check results by keyword Quasi, if they are different, please check by other program like MOLPRO and MOLCAS.}}}  

=== Mixopt ===
{{{#!wiki
  Use approximate Second-Order method for orbital optimization by Werner nonlinear optimization is fluctuating, This is not default when using werner opt, please set this keyword to activate it. This is useless when you use quasi to MO opt.
}}}


=== Localmc ===
{{{#!wiki
  Use Local MCSCF method for orbital optimization by top-down least-change method or block diagonalization of first-order reduced density matrix from MRCIS calculation by link traint, drt and mrci modules. Default is the former by the following keyword "Ltopdown", if you want to use the latter please set keyword "Lmcnmo".
}}}

{{{Notice: Local MCSCF method only supports to nonsymmetric system by keyword 'nosym'. }}}
{{{Notice: which needs previously to calculate Localmo program at least once to calculate dipole moment, }}}  
{{{Notice: or use fragment Local SCF by pFLMO to form pLMO. }}}  


=== Ltopdown ===
{{{#!wiki
  Use top-down least-change for Local MCSCF method with optimized CMO after CASSCF started from pLMO by previous orbital localization SCF or other initial LMO. This method will provide approximate LMO which can be refined by the following Localmo program with MCORB, which will be optimized faster than without this least-change local MCSCF, particularly for the virtual space localization. This is default local mcscf method.

}}}

=== Lmcnmo ===
{{{#!wiki
  Use Local MCSCF method for orbital optimization which needs to calculate MRCIS by link traint, drt and mrci modules. The idea this decoupling of MRCIS first-order reduced density matrix by block diagonalization of it.
}}}

=== Seleci ===
{{{#!wiki
  Calculate Selected CI with set CSF occupation or set Number of Selected CSF occupations to zero so that i.e. *.select1 and *.select2 on WORKDIR folder can be used to set CSF occupation for different spin and space symmetries.
  Line 1: Set Number of Selected CSF occupations (Nref), active MO number to do Selected CI, and excitation number.
  Line 2 to Line Nref+1: set occupation (2,1,0) respectively to double, single and zero occupation.
}}}
Example:
{{{
SELEREF 
 3 4 2
2200  
2110
2020
}}}

Example:
{{{
SELEREF 
 0 0 2  ! read from file select1 or select2 with maximum 2 electron excitation
}}}

=== Sortact ===
{{{#!wiki
  Line 1: Set Number of sort pairs .
  Line 2: set MO indexes which need to sort to  active space one by one. 
  Line 3: set MO indexes which need to sort out active space one by one.
}}}
Example:
{{{
Sortact
 3
 10 15 20   # this means that MO 10 <=> 12; 15 <=> 13; 20 <=> 14
 12 13 14   # the 10, 15, 20 MOs are sorted to active space while 12, 13, 14 are sorted out, respectively. 
}}}

=== Nature ===
{{{#!wiki
  Print Nature molecular orbitals, This is default.
}}}
{{{Notice: Nature can not be used on Local MCSCF calculation.}}}  

=== QCMO ===
{{{#!wiki
  Print average canonical molecular orbitals.
}}}
{{{Notice: Nature can not be used on Local MCSCF calculation.}}}  


=== NOAOSort ===
{{{#!wiki
  This keyword is used when AOINTs are too many to save. Default is without this keyword, which means that we do resort AOints so that Nint=Nij*Nkl. When this keyword is set, AOINTs are saved as original I >= J and K >= L and IJ >= KL. 

}}}


=== NoGrad ===
{{{#!wiki
  Do not save orbital Hessian to disk, which is used for analytical gradients, default is without this keyword.
}}}

== Parameter keywords ==

=== Macit ===
{{{#!wiki
  Maximum step of Macro iteration. Default : 200
}}}
Example:

=== Micit ===
{{{#!wiki
  Maximum step of Micro iteration. Default : 50 for exact second-order method (Werner); 20 for approximate second-order method (Quasi).
}}}
Example:

=== CIiter ===
{{{#!wiki
  Maximum step of CI Davidson iterations. Default : 200
}}}
Example:

=== Ucutoff ===
{{{#!wiki
  threshold of Uki*Ulj of MO trans in internal orbital optimization. Default : 1.d-8. This parameter will greater influence MO trans efficiency in internal orbital optimization. 
  In general, when the parameter is set to zero. the MO trans will be slower than full four-index MO trans and waste computational time unnecessarily.
}}}
Example:

=== NCIsave ===
{{{#!wiki
  Maximum dimension of CI Hamiltonian Matrix which can be saved on core memory. Default : 20000
}}}
Example:

=== NODE ===
{{{#!wiki
  Maximum DRT node number. The default value is 300000.
}}}
Example:

=== WEI ===
{{{#!wiki
  Maximum DRT WEI number. The default value is 5000000.
}}}
Example:

=== PLOOP ===
{{{#!wiki
  Maximum partial LOOP number. The default value is 1000000.
}}}
Example:

=== NREF ===
{{{#!wiki
  Maximum Ref number. The default value is 10000.
}}}
Example:

=== NVFF ===
{{{#!wiki
  Maximum two electron integral number of active space. The default value is 10000000.
}}}
Example:


=== THRESHMAC ===
{{{#!wiki
  Threshold of CI optimization. Default : 1.d-8
}}}
Example:

=== THRESORB ===
{{{#!wiki
  Threshold of orbital optimization. Default : 1.d-4}}}
Example:

=== PRTCRI ===
{{{#!wiki
  Threshold of CI coefficient which will be printed to output file after MCSCF optimization. Default : 0.05
}}}
Example: