If I am not mistaken, the constraints can be done with respect to some direction. From the description of the GeometryConstraints block:
"(...)The third line fixes all three coordinates of atoms 1 to 10, counted backwards from the last one (you may also specify a given direction, like in center). (...)". So, to fix atom 20 in the x and y directions and let it relax only in the z direction, you would specify %block GeometryConstraints position 20 1.0 1.0 0.0 %endblock GeometryConstraints I remember I used it to fix radial coordinates of atoms in carbon nanotubes and let the z-direction relax. You have to write subroutines only for those constraints that are not implemented (cellside, cellangle, center and rigid). Best regards, Marcos > Dear Clutch, > take a look at GeometryConstraints block in SIESTA manual. Also this > topic was discussed recently on the list, you may search (Buscar en > los archivos). You can fix selected atoms by fixing their positions, > but it seems you have to write a routine to fix atoms in one > direction. Examples of routines are in the manual and also on the list > (by Pablo Aguado). > > > On 11/04/07, Clutch Q. J. Fan <[EMAIL PROTECTED]> wrote: >> Dear SIESTA users: >> >> The atoms can fully relax if you do a relaxation. >> >> But if I want to fix some atoms, while the others can relax. >> >> Or if I want to make some atoms can only relax in z direction but are >> fixed >> in x and y direction. >> >> Can SIESTA do this? >> >> Thanks in advance. >> >> >> Yours Clutch >> >> >> >> >> >> ________________________________ >> ?????????????98???????www.126.com > > > -- > Yurko Natanzon > PhD Student > Henryk Niewodnicza?ski Institute of Nuclear Physics > Polish Academy of Sciences > ul. Radzikowskiego 152, > 31-342 Kraków, Poland > Email: [EMAIL PROTECTED], [EMAIL PROTECTED] > -- 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!
