Hi, I think there a small confusion !! If I well understood the primary mail : > %block GeometryConstraints > position 27 0.1 0.0 0.0 > position 27 0.0 0.0 0.1 > %endblock GeometryConstraints 1.0 and 0.0 indicate logical variables !!! freeze or not the corresponding coordinate (x or z). !!! so, after cheking the subroutines consrt.f and fixed.f, I think freezing a one coordinate of a particular atom should be performed as follow: %block GeometryConstraints routine constr %endblock GeometryConstraints this will direct the program to the subroutine constr.f Finally one has to write a small procedure in constr.f where the forces related to the frozen components (of the target atom) have to be set to 0.0 : fx=0.0 fz=0.0 hope this will help !! Cheers, Imad
Marcos Verissimo Alves <[EMAIL PROTECTED]> a écrit : Seems so. But, if you are really unsure and want to clear any doubts, you can test this kind of block on a smaller system, or use your 55 atom system with a low cutoff, SZ basis set and a finite number of scf/cg steps (3 for each should do the job), just to speed up things and see what happens. Then check the .ANI file using molden, or by yourself... Cheers, Marcos > Dear siesta users, > I have a structure of 55 atoms, numbered from 1 to 55. > I need to freeze the x and z components of atom 27. > How to do this? Is it right like this? > > %block GeometryConstraints > position 27 0.1 0.0 0.0 > position 27 0.0 0.0 0.1 > %endblock GeometryConstraints > > Akli, > Thanks > > > > > > > > ___________________________________________________________________________ > Découvrez une nouvelle façon d'obtenir des réponses à toutes vos questions > ! > Demandez à ceux qui savent sur Yahoo! Questions/Réponses > http://fr.answers.yahoo.com > -- Dr. Marcos Verissimo Alves Post-Doctoral Fellow Condensed Matter and Statistical Physics Sector International Centre for Theoretical Physics Trieste, Italy -------- I have become so addicted to vi that I try to exit OpenOffice by typing :wq! ****************************** Imad BELABBAS PhD candidate SIFCOM/ENSICAEN 6, Boulevard du Marechal Juin 14050 Caen Cedex France Tél : 33 2 31 45 26 54 Fax : 33 2 31 45 26 60 ****************************** --------------------------------- Découvrez une nouvelle façon d'obtenir des réponses à toutes vos questions ! Demandez à ceux qui savent sur Yahoo! Questions/Réponses.