3.21 MCLR -- A Program for Linear Response Calcuations

MCLR computes response calculations on single and multiconfigurational SCF wave functions. One of the basic uses of MCKINLEY and MCLR is to compute analytical hessians (vibrational frequencies, IR intensities, etc). MCLR can also calculate the Lagrangian multipliers for a MCSCF state included in a state average optimization and construct the effective densities required for analytical gradients of such a state. The use of keyword RLXRoot in the RASSCF program is previously required. We postpone futher discussion about MCLR to section 3.22.

It follows an example of how to compute the analytical hessian of an excited state:

 &SEWARD &END
Title
 p-benzoquinone anion. Casscf optimized geometry.
Symmetry
 X Y Z
Square
Basis set
C.ANO-L...4s3p2d.
   C1          .0000000000      2.2783822672       1.3271399214
   C2          .0000000000       .0000000000       2.7374556550
nd of basis
Basis set
H.ANO-L...3s2p.
   H1          .0000000000      4.0361650878       2.3432668589
End of basis
Basis set
O.ANO-L...4s3p2d.
   O1          .0000000000       .0000000000       5.1965257318
End of basis
End of Input

 &SCF &END
TITLE
 p-benzoquinone(-) D2h
OCCUPIED
 8 2 5 1 7 1 4 0
ITERATIONS
40
END OF INPUT

 &RASSCF &END
TITLE
 p-benzoquinone anion. 2B3u state.
SYMMETRY
    2
SPIN
    2
NACTEL
    9    0    0
INACTIVE
    8    0    5    0    7    0    4    0
RAS2
    0    3    0    1    0    3    0    1
CIROOT
 1 1
 1
ITER
50,25
LUMORB
END OF INPUT

 &ALASKA &END
End of input

 &MCKINLEY &END
Perturbation
Hessian
End of input

 &MCLR &END
Thre
0.0001
Print
255
Rassi
Elec
End of input

Keyword ELECtric computes the gradient of the dipole moment. Combined with keyword RASSi, which is used to transform the CI vectors to split GUGA representation and the orbital rotations to AO basis to make the response accessible for state interaction calculations, it allows to compute the transition dipole moment geometry derivatives for further uses.