Adding to Andrei's response, you may want to ensure that your electronic bands and lattice parameters for bulk MoS2 do reproduce published results (you are probably trying to go too fast). Best regards, -Salvador ________________________________________ From: [email protected] [[email protected]] on behalf of [email protected] [[email protected]] Sent: Sunday, January 11, 2015 11:53 AM To: [email protected] Cc: siesta-l Subject: Re: [SIESTA-L] Help regarding structural relaxations for AMoS2NR
> Dear all, > > I am trying to relax an armchair MoS2 nanoribbon. My initial > coordinates are taken from the MoS2 sheet. My .fdf file together with > my intial positions are attached. The problem is that after about 70 > steps of CG relaxation, all the atoms are coming together and the > distances between atoms are much shorter than the initial ones. The > relaxed structure after about 70 steps is attached in elec.XV file. I > have successfully done relaxations for the MoS2 sheet but it seems > that I am not able to relax the nanoribbon. Any helps would be > apprecited. > > Bests, > Mohammad, > Dear Mohammad, some suggestions: 1. If you start a complicated system and a mess comes out, it might be a good idea to try to sort the things out. You have a bit too much of everything: many atoms, 70 CG steps, empty supercell whose dimensions you relax (that does not make sense anyway) etc. How about trying just bulk MoS2 first? Then, if it not not quite to expectations, you can pull different levers: basis, cutoffs, XC etc. If everything works fine, you can proceed to your nanoribbons or whatever. 2. If you expect help on a quite vague issue, it might be a good idea to provide at least the output file. There are not many cases when the error is seen right away from the input file, and to expect the colleagues to repeat your calculations just out of curiosity might be too optimistic. Have a nice day, Andrei Postnikov
