[molpro-user] Strange Occupation Numbers for CIS Natural Orbitals

Benjamin Levine levine at chemistry.msu.edu
Wed Feb 27 22:24:28 GMT 2013


Dear Molrpo Users,
We've recently been calculating CIS natural orbitals using the command:

{cis,-2,trans=2
natorb,2150.2}

and we find something very strange.  For some geometries, some of the occupation numbers of the natural orbitals are greater than 2, and the occupation numbers sum to a number significantly larger than the number of electrons.  I would expect CIS natural orbital occupation numbers to be well behaved (0<=n<=2), but maybe I am incorrect?  I'm writing to ask if anyone else has had this experience, or if they might have any insights or explanations.  Example input and partial output files for a particularly striking case are below.  Thank you for your time and consideration.

All the best,
Ben

--
Benjamin G. Levine
Assistant Professor
Department of Chemistry
Michigan State University
East Lansing, MI

517-355-9715 x169
http://levinegroup.chemistry.msu.edu

Input File:

 memory,200,m
 gprint,civector,orbital
 nosym,noorient
 geomtyp=xyz
 angstrom
  
 geometry={
 6
 ethylene xyz input
 C    0.0000000000  0.0000000000  0.0000000000
 C    1.4052545888  0.0000000000  0.0000000000
 H     -3.0318249E-02 -0.3909261      -1.0828689362
 H     -0.6231545     -0.7603594       0.4650986906
 H    1.9721052763  0.9307625       0.000000    
 H    2.0425070093 -0.8726716     -0.1706819    
 }
  
 basis=6-31g**
  
 {multi
 occ,8
 closed,8
 orbital,2140.2}
  
 {hf
 save,2102.2}
  
 {cis,-2,trans=2
 natorb,2150.2}
  
 put,molden,e-cas-221.molf
---

Partial Output:

...
 States requested for CIS calculation: 2.1
  Spin symmetry: singlet

 Convergence thresholds:  THRVAR = 1.00D-08  THRDEN = 1.00D-06

 Number of core orbitals:           2 (   2 )
 Number of closed-shell orbitals:   6 (   6 )
 Number of external orbitals:      40 (  40 )

 Molecular orbitals read from record     2102.2  Type=RHF/CANONICAL (state 1.1)

 Number of N-1 electron functions:               6
 Number of N-2 electron functions:               0
 Number of singly external CSFs:               240
 Number of doubly external CSFs:                 0
 Total number of CSFs:                         241

 Length of J-op  integral file:               0.00 MB
 Length of K-op  integral file:               0.19 MB

 Integral transformation finished. Total CPU:   0.04 sec, npass=  1  Memory used:   0.58 MW
 

 CIS FOR  1 SINGLET EXCITED STATES OF SYMMETRY 1    STATES:  1
 
 Number of CSF:      240
 

 Iter. Vector     |HC-EC|         E_new-E_old   Excitation energy    Total energy
 
   0     1      0.609007E-01      0.211566E-01     0.0211565984    -77.8329390544                      
 
   1     1      0.104942E-01     -0.633429E-02     0.0148223093    -77.8392733435                      
 
   2     1      0.215701E-02     -0.235623E-03     0.0145866862    -77.8395089666                      
 
   3     1      0.594312E-03     -0.135905E-04     0.0145730957    -77.8395225571                      
 
   4     1      0.125467E-03     -0.675507E-06     0.0145724202    -77.8395232326  Converged           

       CIS-Results for state  2.1: Excitation energy         0.01457242 au        0.397 eV        3198.28 cm-1

  Coefficient     Excitation
     0.99267      8.1 ->  9.1

 Starting CIS properties program.     Author: T. Korona (2006)


 1st order properties for state  2.1, spin symmetry singlet


 Starting Coupled-perturbed Hartree-Fock, convergence threshold= 1.0D-06

 ITER   MIC  DIIS      VAR         VARC       CPU
   1     0     1    0.15D+00    0.21D-02     0.01
   2     9     2    0.99D-02    0.28D-02     0.02
   3     2     3    0.36D-03    0.39D-04     0.03
   4     9     4    0.12D-04    0.23D-05     0.04
   5     6     5    0.45D-06    0.57D-07     0.05

 CPHF convergence reached in  5 macroiterations and   26 microiterations.   Accuracy: 4.5210D-07

 CPHF solution written to record  8501.2

 State  2.1  Dipole moment CIS      0.96776762    -0.60478737    -0.14580920
 State  2.1  <RR(SCF)>=  0.275381E+02 <RR(CIS)>=  0.280551E+02   <RR(CIS)>/<RR(SCF)>=  1.02

 Density matrix saved on record      2150.2 (density set 1)

 Natural orbitals
 ================

   Orb     Occ           Coefficients

                         1 1s      1 1s      1 1s      1 2px     1 2py     1 2pz     1 2px     1 2py     1 2pz     1 3d0  
                         1 3d2-    1 3d1+    1 3d2+    1 3d1-    2 1s      2 1s      2 1s      2 2px     2 2py     2 2pz  
                         2 2px     2 2py     2 2pz     2 3d0     2 3d2-    2 3d1+    2 3d2+    2 3d1-    3 1s      3 1s   
                         3 2px     3 2py     3 2pz     4 1s      4 1s      4 2px     4 2py     4 2pz     5 1s      5 1s   
                         5 2px     5 2py     5 2pz     6 1s      6 1s      6 2px     6 2py     6 2pz  

   1.1    3.5061636   -0.060854  0.131965  0.190108 -0.121394  0.361108  0.115844 -0.160893  0.384271  0.089419 -0.000724
                       0.016854 -0.014980  0.010437 -0.018479  0.010750 -0.033988  0.044585  0.022594 -0.020489 -0.291179
                      -0.057646  0.062891 -0.337526 -0.002779 -0.036415 -0.004187  0.002414 -0.000503 -0.136485 -0.205417
                       0.001014  0.008204 -0.006682  0.012854  0.061103 -0.006675  0.009540  0.006406 -0.082016 -0.161725
                       0.000323  0.001634 -0.007400  0.106245  0.206417  0.000945  0.003297 -0.006341

   2.1    2.0055045    0.015169 -0.029378 -0.032248 -0.076659 -0.047009  0.351827 -0.056081 -0.036683  0.160076 -0.023941
                      -0.002386  0.014747  0.001802 -0.027531 -0.008956  0.041245  0.076439  0.029993 -0.096651  0.183669
                      -0.014779 -0.102193  0.138544 -0.005361  0.004123 -0.023745 -0.006883 -0.000324 -0.251589 -0.272510
                      -0.008044 -0.008404 -0.010089  0.151680  0.145153  0.006678  0.006217  0.004893 -0.010215  0.027782
                       0.001378  0.000636  0.003177  0.043380  0.006534 -0.001991  0.000660  0.002849

   3.1    2.0010903   -0.020521  0.020410 -0.037093  0.248681  0.175746  0.079061  0.062998  0.077781  0.016937 -0.011778
                      -0.004551  0.002088  0.020936 -0.012074 -0.071353  0.126963  0.143428 -0.271660  0.274653  0.114874
                      -0.117870  0.075559  0.057360 -0.005602  0.013983  0.006940  0.009816 -0.011555 -0.114264 -0.134881
                       0.003767  0.001592 -0.005865 -0.126202 -0.077184 -0.002238 -0.003258  0.008663  0.106309  0.071260
                      -0.007420 -0.003931  0.002026 -0.188076 -0.171475  0.003753 -0.007862 -0.000532

   4.1    2.0000939    0.031622 -0.101069 -0.141489  0.146192  0.041530 -0.029942  0.048017  0.016854 -0.011786 -0.002983
                      -0.012352  0.004088  0.009375 -0.000629  0.022052  0.334283  0.292087  0.117608 -0.138169 -0.044128
                       0.045807 -0.067581 -0.019055 -0.010887 -0.009579 -0.009065 -0.004014  0.008631 -0.037153 -0.027501
                       0.001321  0.000840 -0.004195 -0.129829 -0.083838 -0.002758 -0.006390  0.004054  0.079365  0.001257
                      -0.003112 -0.009017  0.000714  0.235094  0.119114 -0.009535  0.013813  0.000495

   5.1    2.0000016    0.984612  0.031293 -0.012143  0.013131 -0.000978  0.000352  0.001124  0.003705  0.002129 -0.000656
                      -0.000121 -0.000324  0.001219  0.000022 -0.124964  0.019256  0.024481 -0.005256 -0.005553  0.001896
                      -0.003989 -0.005117  0.000871 -0.000479 -0.000326 -0.000569 -0.000105 -0.000064 -0.001476 -0.001645
                       0.000072 -0.000389 -0.000801 -0.002481  0.001008 -0.000088 -0.000546  0.000456  0.003637  0.000319
                      -0.000324 -0.000556  0.000080  0.008795  0.002340 -0.000473  0.000670  0.000099

   6.1    1.9999987    0.120765  0.004003  0.008430 -0.021407 -0.000175  0.004580 -0.004776  0.001406  0.002295  0.000848
                       0.001659 -0.000274 -0.001963 -0.000057  1.004785 -0.046081 -0.069749 -0.021499  0.026538  0.006767
                      -0.010500  0.011823  0.004750  0.001580  0.001600  0.001289  0.000398 -0.001323 -0.000442  0.003702
                      -0.000006 -0.000184  0.000035  0.010435  0.008595 -0.000018  0.000500 -0.000248 -0.018213  0.000888
                       0.000893  0.002401 -0.000049 -0.047123 -0.020773  0.002188 -0.003305 -0.000323

   7.1    1.9998260   -0.202527  0.324986  0.304041  0.029583 -0.085378  0.025350 -0.006588 -0.040542  0.009649 -0.006605
                       0.006457 -0.006365  0.007358 -0.002453 -0.043427  0.202191  0.125983 -0.151709 -0.010506  0.036674
                      -0.027313 -0.008958  0.015720 -0.009023  0.003765  0.000725  0.012868 -0.005036  0.101928  0.007665
                       0.002007  0.001479  0.012300  0.174424  0.088431  0.008197  0.009133 -0.005959  0.030553  0.005186
                      -0.003279 -0.003054  0.000753  0.021481 -0.018525 -0.003499  0.002757  0.001381

   8.1    1.9995955    0.022111 -0.025714  0.032452 -0.220567 -0.015617  0.007605 -0.076210 -0.023215 -0.007077  0.004920
                       0.017629 -0.002519 -0.011576 -0.001258 -0.011836  0.042627  0.016175  0.330812  0.321938 -0.017557
                       0.161026  0.148774 -0.011521 -0.004681  0.021557  0.002040 -0.014755 -0.000510  0.013645  0.046797
                      -0.004211 -0.000155 -0.000611  0.097448  0.086209 -0.001208  0.003409 -0.002526  0.286379  0.196287
                      -0.004566 -0.014495 -0.000409 -0.039189 -0.050308  0.004060  0.002867 -0.001338

   9.1    0.0010096    0.050665 -0.387381  0.021947 -0.468369 -0.262320 -0.483818 -0.181414  0.128435 -0.376147  0.006368
                      -0.014782 -0.022676 -0.059769 -0.029994 -0.056992  0.343362  0.048698 -0.518953  0.071319  0.290069
                      -0.306098  0.283593 -0.111820  0.008576 -0.063855  0.013868 -0.040879 -0.107074 -0.121882 -0.755722
                      -0.033983 -0.029999  0.019161 -0.006907  0.385387 -0.002768  0.000591 -0.005741 -0.046235 -0.129901
                      -0.025511  0.008212 -0.018689  0.112216  0.438792  0.002727 -0.000300  0.021658

  10.1    0.0005363   -0.074515  0.229255  0.856816  0.137970 -0.007040 -0.448926  0.009842 -0.196226 -0.202987 -0.114109
                      -0.047689  0.205467 -0.082124  0.119768 -0.004208  0.229035 -0.315184  0.274178 -0.312194 -0.460379
                       0.221581 -0.125436  0.411933  0.021357 -0.092168 -0.114892  0.022339  0.121248 -0.143342 -0.648099
                       0.018608 -0.113853  0.042054  0.050943 -0.295076 -0.000592  0.010065 -0.033039 -0.003526  0.310762
                      -0.014161 -0.000570 -0.022959  0.002073 -0.616268  0.009243  0.013792  0.020642

 Electronic charge:   16.000000

 Natural orbitals saved on record    2150.2 (orbital set 1)

 Starting CIS properties program.     Author: T. Korona (2006)


 1st order properties for state  2.1, spin symmetry singlet


 State  2.1 Transition dipole moment CIS     -0.19268290     0.06979694     0.02140916
 Oscillator strength      0.00082493


  Final Results:
  ==============

  State    Exc. Energy    Total Energy     Weight(S)     Weight(D)      Delta E    Conv   Max. Coef.     Excitation
   2.1     0.01457242     -77.83952323     0.100E+01     0.000E+00    -0.676E-06     Y     0.99267      8.1 ->  9.1


 




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