Hi!
   
  I am writing a little program that implements Seminario's method to compute force constants (Seminario "Calculation of Intramolecular Force Fields from Second-Derivative Tensors, Intl J. Quant. Chem.: Quant. Chem. Sympos. 30, 1271-1277 (1996)). The motivation is that this methods generates force constants that are invariant to the choice of internal coordinates.
   
  I noticed that in the internal order of the cartesian coordinates, the dummy atom coordinates are listed last. However, when I look at the entry Freq%Hessian_CART of TAPE21 the matrix size implies that the dummy atoms are included (obviously the derivatives are set to zero), and it seems that the entry for the dummy atom (either row or column given the symmetry of the matrix) corresponds to the input coordinates.
   
  This is evident in the frequency example run provided by ADF for NH3. (Second run where a geometry optimization is done together with the frequency computations).
   
  Am I correct in my interpretation? Also, in general TAPE21 uses column or row order in printing matrices?
   
  Thanks!
  Gustavo Mercier MD,PhD
  gamercier_at_yahoo.com

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Gustavo A. Mercier, Jr. MD,PhD
Baylor University Medical Center
Radiology
American Radiology Associates
712 N. Washington, Suite 101
Dallas, TX 75246
214-826-8822
214-826-9792 fax
gamercier_at_yahoo.com