Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revision Previous revision
Next revision
Previous revision
del_parameter [2015/08/14 10:13]
johnsoevans
del_parameter [2019/07/26 17:14] (current)
johnsoevans
Line 1: Line 1:
-====== del parameter ====== 
 ====== del parameter ====== ====== del parameter ======
 The del parameter is important when searching for a minimum of the penalties as a function of an independent parameter. For example, for each independent parameter ‘x’ the minimum of the penalties P is determined using ‘del’. ‘del’ is set automatically for parameters that Topas knows about (fractional coordinates,​ temperature factors, etc). The del parameter is important when searching for a minimum of the penalties as a function of an independent parameter. For example, for each independent parameter ‘x’ the minimum of the penalties P is determined using ‘del’. ‘del’ is set automatically for parameters that Topas knows about (fractional coordinates,​ temperature factors, etc).
Line 18: Line 17:
    endif    endif
    Loop    Loop
-   +  
 +Some built in values are: 
 + 
 +<code topas> 
 + 
 +cell parameter ​      %min = Max(1.5, 0.995 Val - .05);  %max = 1.005 Val + .05;         del = 0.0001 Val; 
 +cell angle           %min = Max(1.5, Val - .2);         %max = Val + .2;                del 0.01 
 +scale                 min 1e-15                                                         del = Abs(Val) 0.003 + 1e-10; 
 +fractional_coordinate min = Val-Constant(1/​Get(a)); ​     max = Val+Constant(1/​Get(a)); ​ del = Constant(.1 / Get(a));  
 +sh_Cij_prm ​           min = -Abs(Val) 2 - .1;            max =  Abs(Val) 2 + .1;        del = If(Val < 0, -0.01, .01) + .01 Val; 
 + 
 +</​code>​ 
 +  ​
  

Personal Tools