Subject: problems with geometry optimization in GAMESS

From: Dmitry Rozmanov <dima*at*xenon.spb.ru>
Date: Mon, 23 Feb 2004 04:29:17 +0300

Dear Colleagues,

When doing the geometry optimization in GAMESS with PCM or EFRAG solvent 
models I somtimes get a warning and an error I do not understand fully.

the Warning is:
-----------------------------------------------------------------------
           MAXIMUM GRADIENT =  0.0056322    RMS GRADIENT = 0.0015673
           HESSIAN UPDATED USING THE BFGS FORMULA
           WARNING! HEREDITARY POSITIVE DEFINITENESS ENDANGERED
  LOCAL CURVATURE   1 OF THE APPROXIMATE HESSIAN HAS EIGENVALUE=   -2.359644
  *** THIS MODE HAS AN INCORRECT CURVATURE ***
  THE COMPONENTS OF THIS MODE FOLLOWS:
         0.026670       0.061379       0.028994       0.024042   0.016821
-----------------------------------------------------------------------

and the error is:
-----------------------------------------------------------------------
MAXIMUM GRADIENT =  0.0056247    RMS GRADIENT = 0.0015198
           HESSIAN UPDATED USING THE BFGS FORMULA
  ERROR! NOT 5 OR 6 TR MODES
-----------------------------------------------------------------------

After the error I can restart the calculation using the last coordinates 
and it goes ok until the next error of this king or till a success. I 
Cannot say what negative effect "INCORRECT CURVATURE" does though.

So, what do these things mean? And what should and can I do about them? 
I have to restart my calculations 3-4 times to locate a stationary poing 
because of this error. This cannot be right after all.

I get these messages with both summer and december 2003 GAMESS (US) 
compiled with IFC 7.1.

Thank you in advance.
Best wishes.

	---Dmitry Rozmanov.