[molpro-user] Simple unreasonable norm problem...

[Charles Wood]

Hi Molpro mailling list,

I apologise in advance if this is a simple problem to fix. I looked on 
the mailing list's previous thread to no avail.

My problem is this:
I am trying to run an extremely simple H - Ca2+ - H calculation (one 
calcium 2+ ion centred between 2 hydrogen atoms). I'm using UHF and 
UCCSD(T) programs in molpro2009.1. If the geometry is specified so each 
of the H atoms are less than 1.5 Angstroms then the calculation works fine.

If the H atoms are equal to or more than 1.5 Angstroms from the Ca2+ 
ion, I get an unreasonable norm and an unconverged calculation. The 
input file and output error are at the tail of this message.

I saw some people suggest 'shift' but this looks like something 
connected to the geometry....any idea??

Thank you for any help!
Charlie
*************
INPUT:
*************
***,HHCa
  memory,64,mw
  print,basis,orbitals
 
 geomtyp = xyz
 symmetry,nosym
 angstrom
 geometry={
 3,

 h  -1.5   0.0   0.0
 h   1.5   0.0   0.0
 ca  0.0   0.0   0.0
 end
 }
 
basis=vdz
wf,20,1,0
 
 rhf
 uccsd(t)
 ---

*****************
OUTPUT ERROR:
*****************
Starting UCCSD calculation

 ITER.      SQ.NORM     CORR.ENERGY   TOTAL ENERGY   ENERGY 
CHANGE        DEN1      VAR(S)    VAR(P)  DIIS     TIME
   1      1.09064786    -0.06995192  -676.96454186    -0.06995192    
-0.01242820  0.11D-02  0.11D-01  1  1     0.02
   2      1.19987435    -0.09555561  -676.99014555    -0.02560369    
-0.00078764  0.17D-03  0.36D-03  2  2     0.02
   3      1.20574077    -0.09615967  -676.99074961    -0.00060406    
-0.00003603  0.21D-04  0.11D-04  3  3     0.03

 UNREASONABLE NORM. CALCULATION STOPPED

 Norm of t1 vector:      0.08966229      S-energy:     0.00000000      
T1 diagnostic:  0.04483114
                                                                       
D1 diagnostic:  0.06340081
 Norm of t2 vector:      0.44463631      P-energy:    -0.09615967
                                         Alpha-Beta:  -0.09615967
                                         Alpha-Alpha:  0.00000000
                                         Beta-Beta:    0.00000000

 Doubles amplitudes (print threshold =  0.500E-01):

         I         J         SYM. A    SYM. B    A         B      T(IJ, 
AB) [Alpha-Beta]

         1         1         1         1         1         1     -0.41754002
         1         1         1         1         1         9     -0.06746129
         1         1         1         1         1        20      0.06808800
         1         1         1         1         9         1     -0.06746129
         1         1         1         1        20         1      0.06808800

 ?ERROR: NO CONVERGENCE. TRIPLES WILL NOT BE DONE. THIS CAN BE AVOIDED 
USING THE NOCHECK OPTION.

 Spin contamination <S**2-Sz**2-Sz>     0.00000000


 RESULTS
 =======

  Reference energy                   -676.894589937024
  UCCSD singles energy                  0.000000003496
  UCCSD pair energy                    -0.096159674326
  UCCSD correlation energy             -0.096159670830

 !RHF-UCCSD energy                   -676.990749607853

 Program statistics:

 Available memory in ccsd:                63999882
 Min. memory needed in ccsd:                 28044
 Max. memory used in ccsd:                   28044
 Max. memory used in cckext:                 52759 ( 3 integral passes)
 Max. memory used in cckint:                134726 ( 1 integral passes)


 ? Error
 ? No convergence. This error exit can be avoided using the NOCHECK option
 ? The problem occurs in ccsd