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Second experimental data set is submitted
October 03, 2014, 20:00 MSD
We submitted a new series of workunits (12289 wus). Each Wu runs local search for 32 times. So in total 131072 local searches are expected. The precision was set to 0.00001. 10 free parameters for Tersoff potential are fitted.


First experimental data set is submitted
October 03, 2014, 20:00 MSD
We submitted a series of workunits (4096 wus). Each Wu runs local search for 32 times. So in total 131072 local searches are expected. The precision was set to 0.00001. 10 free parameters for Tersoff potential are fitted.


New application is deployed!
October 03, 2014, 20:00 MSD
OPTIMA@home now hosts new application aimed at fitting parameters of the Tersoff potential. Molecular dynamics (MD) is often used for modeling various properties of crystals. The essence of this method consists in the numerical solution of the differential equations describing motion of atoms in the crystal lattice to determine the steady state. For molecular-dynamic computations, you must know the potential - a function that determines the interaction energy of atoms in the lattice. Modern potentials used in the simulations contain several parameters. Specific parameter values determine what concrete material is modeled. For example, for silicon, this will be one set, for diamond another etc. The project is aimed at fitting parameter values of the potential in order to achieve known material properties (energy of the lattice cell, the components of the elastic modulus etc.). Then this potential will be used for molecular dynamics simulation. To identify potential parameters we solve the problem of minimizing the variance of the values of the properties obtained by using the potential from known values. This task is to generate a large sequence of initial approximations, from which further methods local search is a (local) minimum. Next, from the obtained values we select tuples with objective values less than the specified precision.


New test set was launched!
July 08, 2014, 20:00 MSD
It is need for the optimization of the solver smallexpx.


About smallexp and smallexpx
July 18, 2013, 00:01 MSD
Since March, the project carried out calculations associated with the application smallexp. The scientific problem of smallexp is the experimental calculation of the asymptotic growth of the maximum possible number of fragments in a sequence fixed length. It is important to get information on possible periodic structures. This is necessary for the development of efficient algorithms search for fragments of small order in character sequences (the order - the ratio of the length of the words to the minimum period). It's important for discrete mathematics. Smallexpx application has more efficient algorithm then smallexp application.

Articles about scientific problem:

R. Kolpakov, G. Kucherov, On Maximal Repetitions in Words, J. Discrete Algorithms 1(1) (2000), 159–186.

R. Kolpakov, G. Kucherov, Periodic structures in words, chapter for the 3rd Lothaire volume Applied Combinatorics on Words, Cambridge University Press, 2005.

M. Crochemore, C. Iliopoulos, M. Kubica, J. Radoszewski, W. Rytter, T. Walen, Extracting powers and periods in a string from its runs structure, Lecture Notes in Comput. Sci. 6393 (2010), 258–269.


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