On 07/18/2011 09:40 AM, Amin Torabi wrote: > Dear experts! > > Forgive me for my naive question... but I am interested in > pressure-induced phase transitions of diborane. Could you please have a > look at my input file, attached to this message. > > The following is what I think I should do: (correct me if I'm wrong!) > > 1. doing separate vc-relax calculation at each pressure
By using this method, there are some limitations. You should have known in advance the different phases between them the phase transition maybe occur when we change the pressure. Then you can use this method to determine the phase transition path. But I'm not so sure this method can predict all of the possible phases for a system when we change the external pressure. To do a more reasonable and complete phase transition prediction and even searching for unknown phases, you should use some third-party code like uspex for this type of job. In addition, I think you should do relax, not vc-relax calculation at each pressure. If you do vc-relax, then the pressure imposed to the system will be released. So you won't get the *Pressure-induced* phase transition. > 2. comparing the optimized cell_parameters at each pressure to see when > the structure changes > > I am wondering how I can use the enthalpy or unit cell volume at each > pressure to make sure that a phase transition has occurred For the other questions, see this thread on this list: About the method to obtain the common tangent for determing the phase transition pressure. HTH. Regards > > Thanks in advance > > > -- > Amin Torabi > Ph.D. Student > Chemistry Department > /The/ University /of/ Western Ontario > London, On Canada, N6A 5B7 > Phone: 519-661-2111 Ext: 87871 > **************************************** > > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum -- Hongsheng Zhao <zhaohscas at yahoo.com.cn> School of Physics and Electrical Information Science, Ningxia University, Yinchuan 750021, China
