Hi Bernhard,
In phenix.refine, the chiral volume is computed from the ideal bond lengths and
angles,
using the unit cell trick pointed out already by George:
uc = uctbx.unit_cell( [bond.value_dist for bond in bonds]
+ [angle.value_angle for angle in angles])
if (volume_sign.startswith("neg")):
return -uc.volume()
return uc.volume()
The esd isn't defined in the monomer library files. In phenix.refine it is
defined by
this parameter:
chir_volume_esd = 0.2
I believe this is the same value as used in refmac.
Ralf
----- Original Message ----
From: Bernhard Rupp <[email protected]>
To: [email protected]
Sent: Friday, April 3, 2009 9:21:03 PM
Subject: [ccp4bb] chiral volume target value
Dear All,
assuming the chiral volume definition with r() a Cartesian position vector
Vc = [r(N)-r(Ca)]*([r(C)-r(Ca)]x[r(Cb)-r(Ca)])
I always get about -0.65 A**3
Is this correct? Are there any target values?
In a SHELX manual I read + 2.5 for the chiral volume - seems to
be different.
(not to be confused with the pseudo-torsion target of +34 deg)
Thx, BR
