[molpro-user] RCCSD(T) Convergence

[Constantine Koukounas]

Dear Molpro users,
  I am trying to perform an open-shell RCCSD(T) calculation on a
triatomic system. The total energy seems to have converged after ~40-50
iterations, since the total energy doesn't change further. However, the
calculation still  proceeds, and after 150 or 200 iterations, I get a NO
CONVERGENCE message, as follows:
*****************************************************************************************************

 ITER.       NORM       CORR.ENERGY   TOTAL ENERGY   ENERGY
CHANGE        DEN1      VAR(S)    VAR(P)  DIIS     TIME
   1      1.18914054    -0.43378699  -961.48902693    -0.43378699
-0.02124914  0.12D-01  0.75D-02  0  0    27.89
   2      1.23387070    -0.45244735  -961.50768729    -0.01866036
-0.00453653  0.17D-02  0.34D-02  0  0    50.30
   3      1.26543736    -0.45559652  -961.51083646    -0.00314917
-0.00201435  0.21D-02  0.12D-02  1  1    72.88
...
...
...
  57      1.56115670    -0.46740795  -961.52264788    -0.00000002
-0.00000003  0.63D-07  0.71D-08  6  4  1284.58
  58      1.56115851    -0.46740794  -961.52264787     0.00000001
-0.00000003  0.63D-07  0.71D-08  6  4  1307.17
  59      1.56115727    -0.46740795  -961.52264788    -0.00000001
-0.00000003  0.63D-07  0.71D-08  6  4  1329.64
  60      1.56115812    -0.46740794  -961.52264788     0.00000001
-0.00000003  0.63D-07  0.71D-08  6  4  1352.05
  61      1.56115754    -0.46740794  -961.52264788     0.00000000
-0.00000003  0.63D-07  0.71D-08  6  4  1374.57
  62      1.56115794    -0.46740794  -961.52264788     0.00000000
-0.00000003  0.63D-07  0.71D-08  6  4  1396.90
  63      1.56115766    -0.46740794  -961.52264788     0.00000000
-0.00000003  0.63D-07  0.71D-08  6  4  1419.44
...
...
...
 146      1.56115777    -0.46740794  -961.52264788     0.00000000
-0.00000003  0.63D-07  0.71D-08  6  4  3282.52
 147      1.56115777    -0.46740794  -961.52264788     0.00000000
-0.00000003  0.63D-07  0.71D-08  6  4  3305.07
 148      1.56115777    -0.46740794  -961.52264788     0.00000000
-0.00000003  0.63D-07  0.71D-08  6  4  3327.60
 149      1.56115777    -0.46740794  -961.52264788     0.00000000
-0.00000003  0.63D-07  0.71D-08  6  4  3350.13

 Norm of t1 vector:      0.22511323      S-energy:    -0.00365904
T1 diagnostic:  0.08760073
 Norm of t2 vector:      0.33604454      P-energy:    -0.46374891
                                         Alpha-Beta:  -0.35218917
                                         Alpha-Alpha: -0.07106553
                                         Beta-Beta:   -0.04049421

 ?CONVERGENCE NOT REACHED AFTER MAX. ITERATIONS
************************************************************************************************************************

   Does anybody know how to deal with this?
Thank you.
Constantine
--
Constantine Koukounas
National and Kapodistrian University of Athens
Department of Chemistry
Laboratory of Physical Chemistry
PO Box 64004, 157 10 Zografou
Athens-Greece
---
tel :+(3210)7274551, 7274569
fax :+(3210)7274752
e-mail :kkoukoun at chem.uoa.gr