how to calculate valence with BVS in vesta

[tiorfan jaber]

Hello,

Please help me to calculate the valence of metal with Bon valence sum on vesta
i dont know

thanks

[Philip Howie]

Hello Tiorfan,

VESTA doesn't include any utility for automatically calculating the bond valence sum.  However, you can calculate it manually.  The bond distances can be measured using the distance tool at the left of the screen (two atoms with a double-ended arrow between them) and clicking on the two atoms involved; the result, in Ångströms, is displayed in the console at the bottom of the window.

The valence of each bond is then:

v = exp ((R - R0) / B)

where R is the bond length and R0 and B are parameters which can be obtained from
http://www.iucr.org/resources/data/data-sets/bond-valence-parameters

The bond valence sum for an atom is then the sum of the individual valences of the bonds to that atom.

Hope that helps,
Philip

[tiorfan jaber]

Thank you very much

Regards

[Koichi Momma]

Hi Tiorfan and Philip,

Thank you for helping new users, Philip!
By the way, for a very simple case, VESTA can calculate BVS.

First of all, define bonds create coordination polyhedra. Select a polyhedron while pressing Ctrl key. Then you will be asked to input the parameter R0. BVS of the central atom of the polyhedron will be output to the text area.

Then you will also be asked to input oxidation number of the central atom, and a bond distance expected from the oxidation number and R0 will be output to the text area.

Because you can only input one R0 parameter, you cannot calculate BVS correctly when more than two types of elements are coordinated to the central atom. BVS of the coordinated atoms are also not calculated. In such cases, you need to calculate BVS manually.

There was also a typo in the users manual of VESTA.
The valence of each bond is given by
/v/ = exp ((/R/0 - /R/) / /B/)
(R=l and R0=l0 in the manual, and order of l and l0 was opposite.)

The latest list of R0 parameters, bvparm2013.cif, is included in the distribution file of VESTA.

With best regards,
Koichi


Philip Howie wrote on 4/21/15 9:31 PM:

> Hello Tiorfan,
>
> VESTA doesn't include any utility for automatically calculating the bond valence sum. However, you can calculate it manually. The bond distances can be measured using the distance tool at the left of the screen (two atoms with a double-ended arrow between them) and clicking on the two atoms involved; the result, in Ångströms, is displayed in the console at the bottom of the window.
>
> The valence of each bond is then:
>

> /v/ = exp ((/R/ - /R/0) / /B/)
>
> where /R/ is the bond length and /R/0 and /B/ are parameters which can be obtained from

> http://www.iucr.org/resources/data/data-sets/bond-valence-parameters
>
> The bond valence sum for an atom is then the sum of the individual valences of the bonds to that atom.
>
> Hope that helps,
> Philip
>
>
> On Tuesday, 21 April 2015 09:42:24 UTC+1, tiorfan jaber wrote:
>
> Hello,
>
> Please help me to calculate the valence of metal with Bon valence sum on vesta
> i dont know
>
> thanks
>

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--
Koichi Momma
National Museum of Nature and Science
4-1-1 Amakubo, Tsukuba, Ibaraki 305-0005, Japan
TEL: +81-(0)29-853-8163
FAX: +81-(0)29-853-8998
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[Philip Howie]

I learn something every day! ;-)

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