| 查看: 596 | 回复: 1 | |||
| 【悬赏金币】回答本帖问题，作者qdbxj将赠送您 100 个金币 | |||
qdbxj木虫 (小有名气)
|
[求助]
三元素占有率无序精修还可以用fvar命令吗 已有1人参与
|
||
|
请教一下各位老师，书上只有两种原子占有率无序的精修方法。 fvar xx xx part 1 xxxx part 2 xxxx part 0 如果我在同一位置存在三种原子的无序，还可以用fvar或者类似的方法解决吗 |
回复此楼» 猜你喜欢
求高校合作
已经有1人回复
-
27级无机化学申博自荐
已经有2人回复
-
无机化学论文润色/翻译怎么收费?
已经有261人回复
-
Chemdraw免费软件
已经有0人回复
-
单晶结构解析，各类疑难晶体数据处理和答疑
已经有38人回复
-
这个水相反应有没有催化剂促进发生
已经有4人回复
-
Mn Me3TACN
已经有5人回复
-
求助最新的CCDC数据库升级包
已经有0人回复
-
高中化学教师求助：配合物一水硫酸四氨合铜的紫外可见吸收光谱数据
已经有2人回复
-
ACS omega，返修返回去目前为in peer review，求助进度问题
已经有2人回复
雪国郭靖
金虫 (小有名气)
- 应助: 40 (小学生)
- 金币: 3655.6
- 红花: 8
- 帖子: 222
- 在线: 119.6小时
- 虫号: 1435077
- 注册: 2011-10-10
- 性别: GG
- 专业: 物理有机化学
【答案】应助回帖
感谢参与，应助指数 +1
|
用上SUMP命令就行了，下面是教程复制过来的 SUMP c sigma c1 m1 c2 m2 ... The linear restraint: c = c1*fv(m1) + c2*fv(m2) + ... is applied to the specified free variables. This enables more than two atoms to be assigned to a particular site, with the sum of site occupation factors restrained to be a constant. It also enables linear relations to be imposed between distances used on DFIX restraints, for example to restrain a group of atoms to be collinear. sigma is the effective standard deviation. By way of example, assume that a special position on a four-fold axis is occupied by a mixture of sodium, calcium, aluminium and potassium cations so that the average charge is +2 and the site is fully occupied. The necessary restraints and constraints could be set up as follows (the program will take care of the special position constraints on the coordinates and Uij of course): SUMP 1.0 0.01 1.0 2 1.0 3 1.0 4 1.0 5 ! site fully occupied SUMP 2.0 0.01 1.0 2 2.0 3 3.0 4 1.0 5 ! mean charge = +2 EXYZ Na1 Ca1 Al1 K1 ! common x, y and z EADP Na1 Ca1 Al1 K1 ! common U or Uij FVAR ... 0.20 0.30 0.35 0.15 ! starting values for free variables Na1 ... ... ... ... 20.25 ... ! 0.25*fv(2) Ca1 ... ... ... ... 30.25 ... ! 0.25*fv(3) Al1 ... ... ... ... 40.25 ... ! 0.25*fv(4) K1 ... ... ... ... 50.25 ... ! 0.25*fv(5) This particular refinement would probably still be rather unstable, but the situation could be improved considerably by adding weak SUMP restraints for the elemental analysis. Such SUMP restraints may be used when elements are distributed over several sites in minerals so that the elemental composition corresponds (within suitable standard deviations) to an experimental chemical analysis. SUMP may also be applied to EXTI and BASF parameters, including parameters used to describe twinning (TWIN). The parameters are counted in the order overall scale and free variables, BASF, thenEXTI. These virtual free variable numbers are the same as the parameter numbers printed in the .lst file for each refinement cycle. |
2楼2020-09-01 09:13:17
