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Keywords:

  • WebMTA;
  • ab initio methods;
  • cardinality guided molecular tailoring approach;
  • geometry optimization;
  • energy;
  • gradients;
  • density matrix;
  • Hartree-Fock method;
  • density functional theory;
  • large molecule

Abstract

A web-interface for geometry optimization of large molecules using a linear scaling method, i.e., cardinality guided molecular tailoring approach (CG-MTA), is presented. CG-MTA is a cut-and-stitch, fragmentation-based method developed in our laboratory, for linear scaling of conventional ab initio techniques. This interface provides limited access to CG-MTA-enabled GAMESS. It can be used to obtain fragmentation schemes for a given spatially extended molecule depending on the maximum allowed fragment size and minimum cut radius values provided by the user. Currently, we support submission of single point or geometry optimization jobs at Hartree-Fock and density functional theory levels of theory for systems containing between 80 to 200 first row atoms and comprising up to 1000 basis functions. The graphical user interface is built using HTML and Python at the back end. The back end farms out the jobs on an in-house Linux-based cluster running on Pentium-4 Class or higher machines using an @Home-based parallelization scheme (http://chem.unipune.ernet.in/∼tcg/mtaweb/). © 2008 Wiley Periodicals, Inc. J Comput Chem, 2009