ired problem

[175116]

Hello,

I have several chemically-identical systems which slightly differ in the torsion angles only. At first I define some torsions to be fixed during optimization (define: i -> idef -> f tors a b c d ) and then I use ired keyword within define module. For all conformers but one this worked just fine. The one problematic conformer makes the define module end abnormally with this error message, no matter the torsions have been previously fixed or not:

Code: [Select]

ired

 IDENTIFIED TERMINAL RING OF SIZE  5
 ATTACHED TO BRIDGE HEAD ATOM    9


 IDENTIFIED TERMINAL RING OF SIZE  5
 ATTACHED TO BRIDGE HEAD ATOM   16

     GEOSPY: NBDIM:     129  NDEGR:     129
      ATTENTION! Lowest Eigenvalue
      of BmBt is:          0.0000003422
     GEOSPY: ATTENTION!
     natural internals not linearly independent?
       Decoupling with "globtry"=   0.999999999900000     
     GEOSPY: ATTENTION!
     natural internals not linearly independent?
 smfa: Attention! Not enough linearly independent
       redundant internal coordinates
       increase "eigen_quotient" in $redund_inp?
         eigen_quotient real_value
       Threshold is at the moment:    1000.00000000000     

 IDENTIFIED TERMINAL RING OF SIZE  5
 ATTACHED TO BRIDGE HEAD ATOM    9


 IDENTIFIED TERMINAL RING OF SIZE  5
 ATTACHED TO BRIDGE HEAD ATOM   16

     GEOSPY: NBDIM:     129  NDEGR:     129
      ATTENTION! Lowest Eigenvalue
      of BmBt is:          0.0000003422
 
 MODTRACE: no modules on stack

 M-1: Attention! Not enough linearly independent coord.
 define ended abnormally
 define ended abnormally
program stopped.

How can I overcome this problem? Thank You very much indeed.

[uwe]

Hi,

try to add

$redund_inp
  metric 1

to the control file and rerun define. Calling ired will now result in a different mode of automatic generation of internal redundant coordinates which is not based on the 'old' internal coordinates but on pure redundant ones. Usually the resulting coordinates are very similar (or identical), but in cases where the old internal coordinates are really bad it helps.

Regards,

Uwe

[175116]

Hi Uwe,

thank You very much! Using the redund_imp metric 1 keyword I've managed to generate the redundant coordinates. I will let you know whether the optimization process works properly.

[175116]

Hi Uwe, the optimization run has successfully ended  , Thank You very much for Your help one more time