[Pw_forum] Constraints HOWTO

[Jairo Arbey Rodriguez Martinez]

Dear Dr. Carlo Sbraccia and users

I am making a constraint that forces an atom to move on a plane
defined by A*x + B*y +C*z = D, where (x,y,z) is the position of the
atom. I have followed the detailed instructions of the manual
"constraints_HOWTO.pdf", but what I made does not work. The atom moves
freely. I attach the two modules read_cards.f90 and
constrains_module.f90 with the new constraint, and I hope to get help.
The code compiles, links and executes well, but the constraint does
not work.

The lines in the input are:
--------------------------------------------------------------
CONSTRAINTS
1       0.5D-6
mov_on_plane  1     -6.178444739    2.007498388   0.000000000  0.000000000
--------------------------------------------------------------
Some lines of the output are:
     Waiting for input...
     Reading   1 constraints; tolerance:    0.000000
     1) atom   1 is restricted to move on the plane/line
        -6.17844474    * X +  2.00749839    * Y +  0.00000000    * Z =
 0.00000000
...
...  constr target set (n= 1) =  T
   constr_target on atom  1 =  0.00000000
...
...
---------------------------------------------------------------
After that, nothing is mentioned in the output about the constraint.
The scf cycles and the relaxation of the ions seem normal. Thanks in
advance for your help
-- 
Jairo Arbey Rodríguez M.
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