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Hi Haydyn-- > Is there a particular reason that Xplor-NIH scripts do not not use the > dihedral force field term (eg. flags include dihe end)? I realise that > we tend to use refinement against database potentials, and also that the > parameter files generally used are based on the CHARMM19 parameters. You have it right: the appropriate database potential is used for rotatable dihedral angles. The fact is that the DIHE term is the weakest empirical term. The charmm folk are still tweaking the backbone potential, and the database potential does a much better job with the sidechains. > I'm just curious as I tried to use the parallhdg5.3.pro/topallhdg5.3.pro > parameter files in Xplor-NIH to be consistent with an ARIA2.0/CNS run, > and use of the dihedral force field is recommended for this protocol. > All the same, you should be able to use the dihe energy term. > Incidently, Xplor-NIH crashed with the following error upon reading the > parallhdg5.3.pro file: > > %COPYST-ERR: ST2MAX too small. Check input file. > Offending string:" DIHEdral CH2E CH1E C O MULT > 6 0.375 1 0.0000 0.3 2 0.0000 0.225 3 0.0000 0.15 4 0.0000 > 0.075 5 0.0000 0.03 " > with length= 133 > Max allowed length of string= 132 > > I suppose this means that the DIHEdral entries in the parameter file are > too long. Is there a way around this? Does anyone think it's worth > trying anyway? > This should work if you just split the long lines so that they're 132 characters or fewer. You've given fodder for a couple of new entries in the FAQ... best regards-- Charles -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.1 (GNU/Linux) Comment: Processed by Mailcrypt 3.5.8 <http://mailcrypt.sourceforge.net/> iD8DBQE//XY/PK2zrJwS/lYRAv1GAJ0cWs5wjpiyb8e3rvnHE8jE8lLTKQCeNC3M es97GVDmEi9hexJLNdjbCJw= =QR19 -----END PGP SIGNATURE-----
