At last the long awaited EAM has finally been programmed for a Chromium system. For the last 10 days, the program was displaying "nan" as the embedding energy and modified energy values. Tried almost everything to get rid of the error, (i) shifted the entire dimension base from amu(A)2/(fs)2 to eV, but with no avail, (ii) knight.abhi suggested that there's a 0/0 computation somewhere, but accounting for that also proved to be of no avail. Guess what the ridiculous error was: too large a timestep (t=10 fs) which was finally reduced to (t=1 fs) to get the program running correctly.
Another code was run for 20x20x20 system for stability, keeping five boundaries fixed and the top surface open so that the surface shrinks. With this setup the average distance between nearest atoms were found out by considering the 8 closest atoms to each atom, after all the closest atoms were selected using a (r<1.5*r0) criterion and sorted. The average distance after 200.000 fs was computed to be 2.65289503 A, whereas the initial bcc lattice was constructed using r0 = 2.754. So, the system shrinkage is accounted for.
Tuesday, December 9, 2008
Saturday, November 22, 2008
Sunday, 23rd November 08, 0100 hrs
Work done till date:
Indentation done for a 20x20x10 Cr (bcc) system with 3 layer Carbon indenter (tetragonal). 2-body Morse potentials used.
L-D Graph obtained but shows multiple maxima.
Porgrams run: (awaiting results)
30x30x20 system with a 10 layer indenter and complete L-D curve (including indenter retreival)
20x20x20 system for surface stability
Issues:
C-Cr potential still dubious.
Imploding surface (a theory which can solve this, but still some pain in tummy)
Indenter size is limited by segmentation error.
Universal Linked List should be applied for the system. Unfortunately SEGFAULT.
System size must be increased. Present system size is about 16 nm long. Conventional systems are 2x10^7 nm atleast. Parallelization critical.
Pending work:
Linked list to be extended to indenter as well. (done today)
Atomic data and initial conditions to be input from a file. (AP)
Program to be parallelized using SMP and threads. (AG)
Genuine Randomization of initial velocities. (AG)
Future Work:
Carbon potentials, Tetragonal shape & 2 body potential
Embedded Atom Method to applied for Chromium system. (AP)
(Requirements) Aquaguard installed outside lab. Graphics Card on one system.
Indentation done for a 20x20x10 Cr (bcc) system with 3 layer Carbon indenter (tetragonal). 2-body Morse potentials used.
L-D Graph obtained but shows multiple maxima.
Porgrams run: (awaiting results)
30x30x20 system with a 10 layer indenter and complete L-D curve (including indenter retreival)
20x20x20 system for surface stability
Issues:
C-Cr potential still dubious.
Imploding surface (a theory which can solve this, but still some pain in tummy)
Indenter size is limited by segmentation error.
Universal Linked List should be applied for the system. Unfortunately SEGFAULT.
System size must be increased. Present system size is about 16 nm long. Conventional systems are 2x10^7 nm atleast. Parallelization critical.
Pending work:
Linked list to be extended to indenter as well. (done today)
Atomic data and initial conditions to be input from a file. (AP)
Program to be parallelized using SMP and threads. (AG)
Genuine Randomization of initial velocities. (AG)
Future Work:
Carbon potentials, Tetragonal shape & 2 body potential
Embedded Atom Method to applied for Chromium system. (AP)
(Requirements) Aquaguard installed outside lab. Graphics Card on one system.
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