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#1 2022-09-14 10:36:50

cymantren
Member
Registered: 2017-09-18
Posts: 37

Ti-atom, d2-case

Hello Users and developers,

I want to calculate the different states of the Ti- d2-configuration, however the calculation seems not to be correct.
First of all using the symmetry-D2h- the scf-calc. was correct, but the CAS(6,8) was not. The RASF-energy is much lesser than that of the scf !

------------------------------

>>> COPY -FORCE OM_Ti-tripl_sym.UhfOrb INPORB

&GATEWAY
Coord
1
Coordinates in Angstrom units
Ti 0.00  0.00  0.00
Basis=Ti.ano-s.Pierloot.17s12p9d4f.8s7p7d4f..,
Title=Ti Triplet in D2h
Group=Full
End of input

&SEWARD
Title=Seward data By Gabedit
End of input

&SCF
Title=SCF data By Gabedit
UHF
ZSpin=2
End of input

&RASSCF
    Title = Ti 3B1g-Zustand: CAS(6,8)
    LUMORB
    SPIN = 3
    NACTEL = 6,0,0 *RAS2,RAS3,RAS1
    INACT = 3 2 2 0 1 0 0 0 *8 MOs=16e
    RAS2 = 2 0 0 2 0 2 2 0 *8 MOs
    CIROOT = 2,2,1
    RLXROOT = 1
End of input

---> D2h

 Total SCF energy                               -848.3999268807

CAS(6,8):

 Wave function specifications:
      -----------------------------

      Number of closed shell electrons          16
      Number of electrons in active shells       6
      Max number of holes in RAS1 space          0
      Max nr of electrons in RAS3 space          0
      Number of inactive orbitals                8
      Number of active orbitals                  8
      Number of secondary orbitals              76
      Spin quantum number                      1.0
      State symmetry                             1

--
-->

Final state energy(ies):
      ------------------------

::    RASSCF root number  1 Total energy:   -845.62261023
::    RASSCF root number  2 Total energy:   -845.61326499

-------------------------------


Then I tried using "no sym" = C1, the calculation seems to be correct,but the RAS -energy of the active space was always " 0.0"  ??
However the calculations seems to be incorrect and the MOs are not in the proper order, BUT the C1 -calculation gave reasonable results.

C!-sym.
-----------------------------------
--->

 Total SCF energy:  -848.4113969208

 
Title: Natural orbitals

      Molecular orbitals for symmetry species 1: a  

          Orbital            1                  2            3              4          5              6           7              8         9            10    
          Energy         -183.2710  -19.3458  -17.7620   -4.9478  -17.7620  -17.7620   -1.8221   -1.8221   -1.8221   -0.2208
          Occ. No.          2.0000    2.0000    2.0000      2.0000    2.0000    2.0000      1.9996    1.9996    1.9996    1.9972


           Orbital           11            12            13         14           15          16           17          18            19        20    
          Energy           -0.0898   -0.0898    0.1711    2.6340    2.6340    2.6340    5.4199    5.4200    5.4201    6.8339
          Occ. No.          1.0000    1.0000    0.0028    0.0004    0.0004    0.0004    0.0000    0.0000    0.0000    0.0000


--> RAS(6,8)


Wave function specifications:
      -----------------------------

      Number of closed shell electrons          16
      Number of electrons in active shells       6
      Max number of holes in RAS1 space          0
      Max nr of electrons in RAS3 space          0
      Number of inactive orbitals                8
      Number of active orbitals                  8
      Number of secondary orbitals              76
      Spin quantum number                      1.0
      State symmetry                             1
--

++    Orbital specifications:
      -----------------------

      Symmetry species                           1
                                                 a
      Frozen orbitals                            0
      Inactive orbitals                          8
      Active orbitals                            8
      RAS1 orbitals                              0
      RAS2 orbitals                              8
      RAS3 orbitals                              0
      Secondary orbitals                        76
      Deleted orbitals                           0
      Number of basis functions                 92
--

++    CI expansion specifications:
      ----------------------------

      Number of CSFs                          1512
      Number of determinants                  1960
      Number of root(s) required                 2
      Root chosen for geometry opt.              1
      CI roots used                              1     2
      weights                                0.500 0.500
      highest root included in the CI            2
      max. size of the explicit Hamiltonian    200


Final optimization conditions:
      ------------------------------

      Average CI energy                                -848.39357908
      RASSCF energy for state  1                   -848.43147864
      Super-CI energy                                -0.00000000
      RASSCF energy change                            0.00000000
      Max change in MO coefficients              -0.421E-03
      Max non-diagonal density matrix element     0.503E-03
      Maximum BLB matrix element                 -0.997E-05
      (orbital pair   4,  20 in symmetry   1)
      Norm of electronic gradient            0.846E-01
--


      Final state energy(ies):
      ------------------------

::    RASSCF root number  1 Total energy:   -848.43147864
::    RASSCF root number  2 Total energy:   -848.35567953

---> MOs
 

   Orbital                 1               2              3             4          5               6          7             8             9        10
      Energy          -183.2162  -21.3583  -17.7305  -17.7287  -17.7262   -2.6771   -1.7411   -1.7366     0.0000    0.0000
      Occ. No.           2.0000    2.0000      2.0000    2.0000    2.0000       2.0000    2.0000    2.0000    1.9952    1.4806


       Orbital                11        12            13        14             15        16             17         18           19          20
      Energy              0.0000    0.0000    0.0000    0.0000    0.0000    0.0000    0.0352    0.1131    0.1158    0.1163
      Occ. No.           1.4466    0.9923    0.0308    0.0046    0.0405    0.0094    0.0000    0.0000    0.0000    0.0000



-----------------------------------



There are 2 Triplets (F,P)  and 3 Singlets (S,D,G) which emerge from this configuration. The triplet-F state is the groundstate.


Please give me some tips, how I can overcome the problems, and/or where are input-mistakes.

Thank you in advance !

Best regards

Alfred

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#2 2022-09-15 08:10:20

Ignacio
Administrator
From: Uppsala
Registered: 2015-11-03
Posts: 1,085

Re: Ti-atom, d2-case

The higher RASSCF energy in D2h could indicate that your choice of inactive and active orbitals is not correct. Double check the identity of the orbitals (in each irrep) before and after the RASSCF calculation. Try first to quasi-reproduce the SCF calculation with a 2-in-2 active space...

Regarding the C1 calculation, the energies of the active (natural) orbitals are undefined, and displayed as zero. If you want defined energies you could compute canonical orbitals, but then the occupations would be undefined. The order of the active orbitals is irrelevant.

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