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Re: [lammps-users] [EXTERNAL] unrealistic values
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Re: [lammps-users] [EXTERNAL] unrealistic values

From: "Thompson, Aidan" <athomps@...3...>
Date: Mon, 25 Sep 2017 15:29:27 +0000

Please post future questions to the mailing list.


Your difficulties probably originate in the complexity of the atomic structures you are working with.  ELASTIC_T works best for systems that have either a single local energy minimum (crystalline solid) or a system that quickly samples the full ensemble of minima (liquid).  Many solid materials lie between these two extremes.  I suggest trying to simplify your problem by either raising or lowering the temperature, or perhaps first doing the zero temperature case with the ELASTIC script.





      Aidan P. Thompson

      01444 Multiscale Science

      Sandia National Laboratories

      PO Box 5800, MS 1322      Phone: 505-844-9702

      Albuquerque, NM 87185     Fax  : 505-845-7442

      E-mail:athomps@...3... Cell : 505-218-1011



From: Laanaiya Majdouline <majdouline.laanaiya@...24...>
Date: Saturday, September 23, 2017 at 3:46 AM
To: "Thompson, Aidan" <athomps@...3...>
Subject: [EXTERNAL] unrealistic values




I'm a PHD french student working on the Calcium-Silicate-Hydrates system, I've just  started working with LAMMPS. I need to calculate the mechanical properties of the structure at T=300°K. I've tried your script on ELASTIC_T example and I unfortunately get very confusing results (for example, found C11= -16773.322 GPa Vs expected 93.3 GPa).


 I've changed the parameters in init.mod and potential.mod files. I'm using real units (cfac changed) and I've changed the MD parameters. The structure is defined by its atomic coordinates (read_data command from file). Though I've tried many times to change the MD parameters, I still can't find where the problem comes from. Can you please have a look at my input files? 


Please find attached all the used input and log files.


Any help is appreciated in advance,


Thank you







Majdouline Laanaiya


Doctorante, Génie Civil.

Laboratoire de Génie Civil et Géo-Environnement (LGCgE)

Cité Scientifique, Avenue Paul Langevin. 59655 Villeneuve d'Ascq

Email : majdouline.laanaiya@...3816...

Tél : 0033 758 79 58 52