AMBER Archive (2008)

Subject: AMBER: value of Pi in Amber

From: Alan (
Date: Fri Aug 08 2008 - 05:36:06 CDT

Hi List!
Ok, it may meaningless in the end but I saw in the prmtop files that
for DIHEDRAL_PHASE, angle 180 degree is given 3.14159400E+00.

Pi is 3.141592653590...., so if rounding as above is should
be 3.14159300E+00.

grepping over amberTools src code, I see Pi apparently correctly defined.

What I am doing in tleap is:
source leaprc.gaff
mods = loadamberparams FOO.frcmod
FOO = loadmol2 FOO_bcc_gaff.mol2
saveamberparm FOO FOO_AC.prmtop FOO_AC.inpcrd

So, if I am loading only leaprc.gaff and FOO.frcmod (generated by
antechamber with gaff), and in both files dihedral phase is written in
degrees (e.g. 180.0), I am wondering in which part of leap code is
converting to 3.14159400E+00.

Many thanks in advance,

Alan Wilter S. da Silva, D.Sc. - CCPN Research Associate
Department of Biochemistry, University of Cambridge.
80 Tennis Court Road, Cambridge CB2 1GA, UK.

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