fatal error in geom calc dihedral
Just Got Here
9:37:52 AM PDT - Wed, Oct 5th 2011
I calculate CDFT of a moleculear of 62 atoms , fatal error in geom_calc_dihedral occured as follows


==============================================================================
                            internuclear dihedral angles

------------------------------------------------------------------------------

   center 1   |   center 2   |   center 3   |   center 4   |  degrees

------------------------------------------------------------------------------

  19 H        |   1 C        |   5 N        |   2 C        |   179.93
... ...
   6 Pd       |   7 N        |  11 C        |   5 N        |     0.06

 fatal error in geom_calc_dihedral 

 mbaxbc        5.950284209926354E-004

 mcbxcd         13.9845127888136     

a coordinates   15.2677959032440       9.000000000090243E-006

-8.999999999972690E-006

b coordinates   10.7583661605949      -1.699999999990976E-005

 2.100000000002731E-005

c coordinates   7.13864542636145      -1.509999999999098E-004

 1.130000000000273E-004

d coordinates   10.0988601606376       -3.03333667777368     

  2.39276801962222     

 angle   abc    179.997911359031     

 angle   bcd    52.5417216081486     

 angle   abd    99.6877275510057     

 angle   acd    52.5405723513803     

 please report this data to:

         nwchem-users@emsl.pnl.gov

------------------------------------------------------------------------

geom_print_dih:geom_calc_dih death      911

------------------------------------------------------------------------

------------------------------------------------------------------------

 current input line : 

  106: task dft optimize

------------------------------------------------------------------------

------------------------------------------------------------------------

There is an error related to the specified geometry

------------------------------------------------------------------------

For more information see the NWChem manual at 

http://nwchemgit.github.io/index.php/NWChem_Documentation




For further details see manual section:
0:0:geom_print_dih:geom_calc_dih death:: 911
(rank:0 hostname:linux-qji0 pid:11367):ARMCI DASSERT fail. armci.c:ARMCI_Error():260 cond:0

Does anybody help me?

Just Got Here
1:34:39 PM PDT - Wed, Oct 5th 2011
Fatal error in geom_calc_dihedral
Hi Zhang,

The problem is that in your case the particular dihedral angle is undefined. The reason is that if you have atoms A-B-C-D then the dihedral angle is defined as the angle between the planes defined by A-B-C and B-C-D. These planes are uniquely defined as long as the atoms A-B-C and B-C-D are not on a line. If they are, however, on a single line there is no unique definition of the dihedral angle. If you check the coordinates print below (a coordinates through to d coordinates ) then you'll see that the atoms A-B-C are almost exactly on a line. Hence the error message you are getting.

This explains what the error is but not why you are getting it. Your geometry optimization must somehow be using internal coordinates (maybe forced by constraints on the geometry) that become ill defined along the optimization pathway. This is very likely highly case specific. So you may want to have a look at the geometry and maybe the optimization pathway that got you to this point. This should give you some information as to why you are hitting this problem.

Best wishes,

    Huub


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