[molpro-user] optg and symmetry

[Sears, John S]

Tim,
The problem is that your z-matrix does not enforce the desired symmetry. Try something like the example I've included below. I tried this optimization with a sto-3g basis and it completed successfully with the desired symmetry. Also, note that the geometry analysis will more readily identify the desired principal axis if you ensure this is defined by the initial two atoms in the z-matrix specification. Hope this helps.
Cheers,
John


geometry={
angstrom;
 c;
 o1, c,oc1;
 o2, c,oc2,o1,oco;
 o3, c,oc2,o1,oco,o2,dih4;
 h1,o2,ho,c ,hoc,o3,dih5;
 h2,o3,ho,c ,hoc,o2,dih5;
}

oc1  =      1.222;
oc2  =      1.222;
ho =       0.88;
oco=       120.000;
hoc=       120.000;
dih4=      180.000;
dih5=         180.000;


----- Original Message -----
From: "lillestolen" <timothy.lillestolen at nottingham.ac.uk>
To: molpro-user at molpro.net
Sent: Wednesday, November 5, 2008 6:24:46 AM GMT -05:00 US/Canada Eastern
Subject: [molpro-user] optg and symmetry

Dear Molpro users,

I feel like I'm probably missing something simple here, but I still
can't figure out what I am doing wrong.  I am trying to optimise the
geometry of carbonic acid (H2CO3) with C2V symmetry at the
B3LYP/aug-cc-pVDZ level of theory.  I am including the  input file at
the end of the message.  The first energy evaluation works just fine,
and the program detects the correct C2V symmetry.  However, after the
first displacements are calculated I get the following error:


Optimization point 1

 Variable                      Last           Current       
Next           Gradient       Hessian

 E(KS-SCF000) / Hartree      0.00000000  -264.87588720     0.00000000
 OC1 / ANGSTROM              0.00000000     1.22200000     1.28411786   
-0.25660683     4.00134221
 OC2 / ANGSTROM              0.00000000     1.22200000     1.25951398   
-0.32956964     8.18713291
 OCO / DEGREE                0.00000000   120.00000000  
119.07590136     0.00134251     0.00164275
 DIH4 / DEGREE               0.00000000   180.00000000  
180.00000000     0.00000000     0.00000000
 HO / ANGSTROM               0.00000000     0.88000000     0.94600782   
-0.41770827     6.28691438
 HOC / DEGREE                0.00000000   120.00000000  
117.35334871     0.00102677     0.00046113
 DIH5 / DEGREE               0.00000000     0.00000000    
0.00000000     0.00000000     0.00000000
 DIH6 / DEGREE               0.00000000   180.00000000  
180.00000000     0.00000000     0.00000000
 Convergence:                0.00000000  (line search)    
0.19172405     0.32724871  (total)
 The request for symmetry elements X,Y, cannot be honoured
 ? Error
 ? Symmetry problem
 ? The problem occurs in zmatrix.f:zmat_orient

 ERROR EXIT
 CURRENT STACK:      MAIN


 **********************************************************************************************************************************
 The request for symmetry elements X,Y, cannot be honoured

 Prototype coordinates
                   1             2             3            
4             5             6
         1     0.0000000     0.0000000     0.0000000     0.0000000    
0.0000000     0.0000000
         2    -0.0240505     1.2534949     1.1355597    -2.4015615    
0.1491318     0.3359890
         3    -0.0252998     2.0378084    -2.1038457     0.0864578   
-3.5947566     3.5720959
 ? Error
 ? Symmetry problem
 ? The problem occurs in zmatrix.f:zmat_orient

 RECURSIVE CALL OF FEHLER. EMERGENCY STOP.
 FILE INFORMATION MAY BE LOST

 RECURSIVE CALL OF ERROR HANDLER, FILE INFORMATION MAY BE LOST

 EMERGENCY STOP


I get the same message if I try and do the optimisation with hartree
fock (replacing ks,b3lyp with hf).  Am I doing something incorrectly
with my z-matrix?  Or is there another option that I am missing out on? 
I really need to get the final geometry with the correct symmetry as I
am calculating some atomic properties using these geometries and I need
symmetric atoms.  Much thanks in advance for any advice/help,

best regards,

Tim Lillestolen
Wheatley Group
University of Nottingham


input file:

***,h2co3

basis=avdz

geometry={
angstrom;
 c;
 o1, c,oc1;
 o2, c,oc2,o1,oco;
 o3, c,oc2,o1,oco,o2,dih4;
 h1,o2,ho,c ,hoc,o3,dih5;
 h2,o1,ho,c ,hoc,o2,dih6;
}

oc1  =      1.222;
oc2  =      1.222;
ho =       0.88;


oco=       120.000;
hoc=       120.000;

dih4=      180.000;
dih5=         0.000;
dih6=       180.000;

ks,b3lyp;
optg,symmetry=auto,coord=zmat;


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-- 
Dr. John S. Sears
Post-doctoral Research Associate
Center for Organic Photonics and Electronics
Center for Computational Molecular Science and Technology
School of Chemistry and Biochemistry
Georgia Institute of Technology
Atlanta, GA 30332-0400
john.sears at chemistry.gatech.edu
Phone: (678)416-0362
Fax: (404)894-7452
Office: MS&E 4202