NCSA Nanotechnology Initiative
Developing and porting code to run on NT and LINUX pentium clusters
global minimization code from
group at Cambridge University, has been parallelized
using MPI directives and used for large benchmark calculations on the
NT cluster and SGI Origin at NCSA, and on an
IBM RS6000 cluster at the University of
The code is also being ported to the
Pentium Beowulf cluster at the
Albuquerque High Performance Computing Center.
This algorithm uses a Monte Carlo "search" to explore configuration space
together with an energy minimization which
transforms the potential energy surface (PES) and effectively removes transition state
The diagram below illustrates how GMIN may change a PES (black)
into a modified "terrace" potential (red).
Unlike many other surface deformation methods, GMIN leaves the
global and local minima unchanged. The transformation increases the probability of
escaping from local minima and facilitates locating the global minimum.
More details on the GMIN algorithm and a brief summary of some of the systems
to which it has been applied may be found here.
Availability of the GMIN code
A scalar version of the GMIN code is available from Wales'
website at Cambridge University.
A parallel version
has been developed as part of the Nanotechnology Initiative by extending the functionality of
The publically released versions of the serial and parallel GMIN codes have built in
Lennard-Jones and Morse potentials. Information on accessing the parallel version of GMIN will
be provided in the near future. If you are interested in using the parallel version of
this code please contact:
Lindsey J. Munro.
Documentation on the parallel version of GMIN
Investigation of binary Lennard-Jones clusters
We are presently using the GMIN algorithm to locate the global minima of large
mixed Ar-Xe, Ar-Ne and Ar-Kr clusters. Particular emphasis is being placed on clusters containing
38 and 75-77 atoms which have proven to be especially challenging for the "unmixed" Ar clusters and,
as a contrast, 55-atom clusters, which has been found to be more straightforward
for the pure Ar55 cluster. The animation to the left shows the global minima of
ArnXem clusters, where n+m=7, and illustrating the
substitution pattern for the Xenon atoms.
The blue and green atoms represent Argon and Xenon respectively. (It may be necessary to press Reload
to view the animation.)
- Implementation of a parallel version of the Jump-Walk algorithm to the Monte Carlo simulations.
- Extension of GMIN to handle protonated water clusters as treated with an effective valence
- Extension of GMIN to handle minimization of negatively charged water clusters.