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Note that the original Nayal & Di Cera algorithm uses an older and less preferred version of the bond valence model and its associated parameters than current implementations of BV. The original WASP uses this formula: bond valence = (Rij/R0)^(-N) The most up-to-date BV parameter set (http://www.ccp14.ac.uk/ccp/web-mirrors/i_d_brown/bond_valence_param/bvparm2006.cif ) uses this: bond valence = exp((Ro-Rij)/B) where Rij is the metal-ligand distance, and R0, N and B are parameters specific to the metal-ligand pair. Obviously these parameter sets may give different results depending on which formula you are using. See the IUCr monograph by I.D.Brown: "The Chemical Bond in Inorganic Chemistry: The Bond Valence Model", chapter 3 for more info. Cheers -- Ian On Tue, Dec 21, 2010 at 8:55 AM, Robbie Joosten <[log in to unmask]> wrote: > You could also try the original WASP here (also for coloured Indo-dutch > catholics): http://xray.bmc.uu.se/cgi-bin/gerard/rama_server.pl or you can > use the latest WHAT_CHECK that also has an implementation of Nayal and Di > Cera's algorithm. > > Cheers, > Robbie > >> Date: Mon, 20 Dec 2010 22:59:53 +0000 >> From: [log in to unmask] >> Subject: Re: [ccp4bb] Mg2+ or water >> To: [log in to unmask] >> >> On 20/12/10 21:48, Robbie Joosten wrote: >> > >> > >> > Also note that Mg2+ is significantly smaller than water. It fits in >> > places where water cannot go. This doesn't look like a magnesium site >> > on first glance. >> >> I tend to agree with Robbie. I wonder what WASP would say... (if you >> use Coot, you can try the "Highly Coordinated Waters" validation test - >> a symmetry-enhanced implementation of the Nayal & Di Cera (1996) >> algorithm). >> >> Paul. >