MCSCF

Multi-configurational self consistent field program.

General keywords

Close

• Number of inactive orbitals in each irreps.

Example:

Active

• Number of active orbitals in each irreps.

Example:

actel

• Number of active electrons in active space.

Example:

RootPrt

• 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

• Symmetry of the target state.

Example:

Spin

• Spin multiplicity. 2S+1

Example 1:

Spin
 1   # singlet

Example 2:

Spin
 2  # doublet

Roots

Three 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

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

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

• 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

• MCSCF calculation with one direct CI step in each micro-iteraction, which may be useful in large CI system, default is .false..

molden

• Output MCSCF orbital into Molden format file.

CIONLY

• Only CI optimization is done.

QUASI

• 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.

NOGRAD

• Do not save orbital Hessian to disk, which is used for analytical gradients. Default is not input this parameter, so that it can be saved.

Parameter keywords

MACIT

• Maximum step of Macro iteration. Default : 20

Example:

MICIT

• Maximum step of Micro iteration. Default : 50

Example:

CIITER

• Maximum step of CI Davidson iterations. Default : 50

Example:

NCISAVE

• Maximum dimension of CI Hamiltonian Matrix which can be saved on core memory. Default : 20000

Example:

NODE

• Maximum DRT node number. The default value is 300000.

Example:

WEI

• Maximum DRT WEI number. The default value is 5000000.

Example:

PLOOP

• Maximum partial LOOP number. The default value is 1000000.

Example:

NREF

• Maximum Ref number. The default value is 10000.

Example:

NVFF

• Maximum two electron integral number of active space. The default value is 10000000.

Example:

THRESHMAC

• Threshold of CI optimization. Default : 1.d-8

Example:

THRESORB

• Threshold of orbital optimization. Default : 1.d-5

Example:

PRTCRI

• Threshold of CI coefficient which will be printed to output file after MCSCF optimization. Default : 0.05

Example: