[molpro-user] atomic MRCI calculation

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Dear molpro user, Recently I made an MRCI calculation for atoms like, B, C,
Li, and so on. I found two problems

 

1.     There are ghost states.

2.     The calculated energies are sometimes lower than the experimental
values.

 

Examination of ci vectors reveals that the ghost states come from the
insufficient specification of the symmetry. With C2v symmetry, 2pz and 2px
have different energies.

    Is there any method, options and so on for the imposition of strict
restrictions so that two mentioned problems go away ? 

 

Sincerely yours,  Chun-Woo Lee

 

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The energies of the first several valence states of a carbon atom are

 

State            E         Exc. E (eV)

3P(2S22P2)   -37.78810854        0.000

1D           -37.74193738        1.256    (ghost state) 

 1D(2S22P2)   -37.74187641        1.258   (lower than exptl. Value 1.260)

1S(2S22P2)   -37.68995308        2.671

5S(2S2P3)    -37.63521157        4.161   (lower than exptl. Value 4.179)

3D(2S2P3)    -37.49527426        7.968 

 

The script file I used to obtain the above energies for the valence states
of a carbon atom is as follows:

 

1.     The basis set is basically av6z with i orbitals removed and the
diffuse component of h orbital is removed

2.     Active space (1s,2s,2p,3d) 

 

************ the script file
****************************************************************************
****

 

***,C 6 valence states with (1s,2s,2p,3d) and 4 Rydberg states with
(1s,2s,2p,3d,3s)

memory, 50, mw

!gprint,basis,orbital,civector

symmetry,x,y

geometry = {C}

basis= {s, C , 312100.0000000, 46740.0000000, 10640.0000000, 3013.0000000,
982.8000000, 354.8000000, 138.4000000, 57.3500000, 24.9200000, 11.2300000,
5.2010000, 2.4260000, 0.9673000, 0.4456000, 0.1971000, 0.0863500, 0.03540

c, 1.11, 0.00000567, 0.00004410, 0.00023190, 0.00097897, 0.00355163,
0.01144061, 0.03299855, 0.08405347, 0.18067613, 0.30491140, 0.34141570

c, 1.11, -0.00000121, -0.00000939, -0.00004947, -0.00020857, -0.00076015, -
0.00245469, -0.00720153, -0.01880742, -0.04325001, -0.08259733, -0.12857592

p, C , 295.2000000, 69.9800000, 22.6400000, 8.4850000, 3.4590000,
1.5040000, 0.6783000, 0.3087000, 0.1400000, 0.0617800, 0.02376

c, 1.5, 0.00014249, 0.00122010, 0.00633696, 0.02351875, 0.06990447

d, C , 4.5420000, 1.9790000, 0.8621000, 0.3756000, 0.1636000, 0.06360

f, C , 2.6310000, 1.2550000, 0.5988000, 0.2857000, 0.1180

g, C , 2.6520000, 1.2040000, 0.5470000, 0.2540

h, C , 2.0300000, 0.8511000, 0.4510}

 

$states =[3P(2s22p2),1D,1D(2s22p2),1S(2s22p2),5S(2s2p3),3D(2s2p3)];

 hf

{multi;occ,5,2,2,1;frozen,1.1;wf,6,4,2;state,1;wf,6,1,0;state,3;wf,6,4,0;sta
te,3

wf,6,1,4;state,1;wf,6,4,4;state,1;wf,6,1,2;state,2;wf,6,4,2;state,2}

{mrcic;occ,5,2,2,1;wf,6,4,2}

e(1) = energy

{ci,nocheck;wf,6,1,0;state,3,1,2,3}

e(2) = energy(1)

e(3) = energy(2)

e(4) = energy(3)

{mrcic;wf,6,4,4}

e(5) = energy

{ci;wf,6,4,2;state,1,2}

e(6) = energy

 de = (e-e(1))*toev

 {table,states,e,de

head,'State','E','Exc. E (eV)'}

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