[molpro-user] CCSD(T) RHF not converging

[Jörg Saßmannshausen]

Dear all,

I am new to MolPro and I am running into a problem. I want to do a CCSD(T) 
calculation of an organic molecule containing N, O, Si and F as heteroatoms. 
The structure was optimised at the MP2 level of theory. 
However, when I try to run a CCSD(T) calculation, the RHF does not converge 
after 40 steps. I have tried to set it to a (rediculus) high number of 300 
with the MAXIT keyword, but somehow that seems to be ignored. Only 40 steps 
are done in the SCF cycle (see below). I am using Version 2008.1 linked 05 
Sep 2008 17:30:47.

Enclosed are the relevant parts of the input file and of the output file.

Any help would be appreciated.

All the best from Glasgow!

Jörg 

Input file:

***, CCSD(T)/cc-pVTZ//mp2/6-31g*
memory,128,m    !128 MW of memory
SET,CHARGE=1    !charge of the molecule is +1
geomtyp=xyz
print,basis,orbitals   !this is optional: print the basis set and the occupied 
orbitals
geometry
   53
Title
[ x,y,z data omitted]
end

gdirect                 !direct SCF
maxit=300
basis=cc-pVTZ           !cc-pVTZ basis set for all elements
hf                      !Perform HF calculation
ccsd(t)                 !Perform CCSD(T) calculation

Output file:
**********************************************************************************************************************************
 LABEL *    CCSD(T)/cc-pVTZ//mp2/6-31g*
 Linux-2.6.16.21-0.25-smp/comp04(x86_64) 64 bit mpp version                              
DATE:  27-Jul-09         TIME: 12:09:28
 
**********************************************************************************************************************************

 Patch level:      5
 
**********************************************************************************************************************************
 SETTING CHARGE         =         1.00000000
 SETTING GEOMTYP        =    XYZ

 SETTING MAXIT          =       300.00000000

 Variable memory set to  128000000 words,  buffer space   230000 words

 SETTING BASIS          =    CC-PVTZ


 Recomputing integrals since basis changed


 Using spherical harmonics

[ ... ]

   39      0.290D-01      0.327D-05      -838.82230741   
5081.656176  -0.490062   8.280986   6.429773    9    692.8  33599.7   diag
   40      0.191D-01      0.253D-05      -838.82234139   
5081.610385  -0.514874   8.284814   6.438603    9    737.5  34337.2   orth


 ?APPARENTLY NO CONVERGENCE, EXIT AFTER THREE FURTHER ITERATIONS


   41      0.330D-01      0.220D-05      -838.82236185   
5081.604467  -0.444846   8.282878   6.450778    9    704.2  35041.4   diag
   42      0.139D-01      0.214D-05      -838.82237696   
5081.606024  -0.554554   8.281759   6.448026    9    702.7  35744.1   orth
   43      0.628D-02      0.250D-05      -838.82237391   
5081.591500  -0.315418   8.277418   6.461300    0    666.8  36410.9   orth

 Final occupancy:  91

 !RHF STATE 1.1 Energy               -838.822373907758
 Nuclear energy                      2661.88013060
 One-electron energy                -6041.49825469
 Two-electron energy                 2540.79575018
 Virial quotient                       -0.59157207
 !RHF STATE 1.1 Dipole moment          -0.31541800     8.27741845     
6.46130011
 Dipole moment /Debye                  -0.80166009    21.03772118    
16.42191113

[ ... ]

CCSD(T)     terms to be evaluated (factor= 1.000)


 Number of core orbitals:          27 (  27 )
 Number of closed-shell orbitals:  64 (  64 )
 Number of external orbitals:    1023 (1023 )

 Molecular orbitals read from record     2100.2  Type=RHF/CANONICAL (state 
1.1)

 ?Error: RHF not converged. This error exit can be avoided using the 
IGNORE_ERROR option on the ORBITAL directive





-- 
*************************************************************
Jörg Saßmannshausen
Research Fellow
University of Strathclyde
Department of Pure and Applied Chemistry
295 Cathedral St.
Glasgow
G1 1XL

email: jorg.sassmannshausen at strath.ac.uk
web: http://sassy.formativ.net

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