|
|
【答案】应助回帖
★ ★ ★
mazuju028(金币+3, 1ST强帖+1): 谢谢交流 2011-07-03 22:49:35
yuhuashi1(金币+10): 非常感谢您的耐心回复！受益匪浅！谢谢~O(∩_∩)O~ 2011-07-04 11:02:15
Opt_Constraint
Purpose
The lines following the Opt_Constraint keyword define constrained internal coordinates (bonds, angles, torsions) in molecules or solids. These internals are held fixed at the values of the initial structure.
Syntax
Opt_Constraint
constraint specifications ...
blank line
Description
For molecular structures the format is:
Opt_Constraint
i j k l
where the integers i, j, k, and l correspond to the numbers of the atoms in the .car file. The following designations are used:
i j 0 0: constrain the bond between atoms i and j
i j k 0: constrain the angle formed by atoms i, j, and k
i j k l: constrain the torsion formed by all 4 atoms.
For periodic structures the format is:
i ia ib ic j ja jb jc k ka kb kc l la lb lc
where i,j,k,l have the same meaning as for molecules, and ia ib ic, etc. indicate which unit cell contains the atom.
These constraints are added automatically when you run via the Materials Studio user interface. Use the Constraints option on the Modify menu to define constraints via the interfaces.
Example
In a molecule to freeze the bond between atoms 5 and 6, the bond between atoms 7 and 8, and the torsion 4-5-6-7 the input is:
Opt_constraint
5 6 0 0
7 8 0 0
4 5 6 7
In a periodic structure, to constrain the bond between atoms 1 and 2 in the same unit cell:
Opt_constraint
1 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0
In a periodic structure, to constrain the bond between atom 3 in one unit cell and the periodic image of atom 4 one cell in the "a" direction:
Opt_constraint
3 0 0 0 4 1 0 0 0 0 0 0 0 0 0 0
To include a second constraint in the above example use:
Opt_constraint
3 0 0 0 4 1 0 0 0 0 0 0 0 0 0 0
2 -1 0 0 3 0 0 0 4 0 1 0 0 0 0 0
This constrains the angle, including the periodic image of atom 2 in the cell in the "-a" direction, atom number 3 in the reference cell, and the periodic image of atom number 4 in the "+b" direction.
将构XYZ三边的四个原子的相互角度固定可能实现你的目的。
2、加电场需要手动加关键词
electric_field
Purpose
The electric_field keyword allows you to specify the value of the external electric field used in the calculation. The field is described in terms of three cartesian components.
Syntax
electric_field value_in_X value_in_Y value_in_Z
command keyword values default meaning
electric_field real real real 0.0 0.0 0.0 The x, y and z components of the electric field applied to the system.
Example
This example is for electric field with strength 0.05 a.u. applied in the Z direction only:
electric_field 0.000 0.000 0.0500 |
|
回复此楼
yuhuashi1
点击这里搜索更多相关资源