[gmx-users] NH2 angles wrong in calch.c

Charles Karney ckarney at sarnoff.com
Tue Nov 16 23:11:07 CET 2004

The documentation of the hydrogen database (Gromacs Manual 3.2, p 94)
says that "type 3" hydrogens are added with bond angles of 120 (which is

However the code, v 3.2.1, src/gmslib/calch.c, lines 182-187, uses the
tetrahedral angle 109.5 deg.  Surely this is wrong.

Minor gripe: why not define the tetrahedral angle exactly?

#define alfaH   (acos(-1/3.0))

Charles Karney                  Email:  ckarney at sarnoff.com
Sarnoff Corporation             URL:    http://charles.karney.info
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