Q (software)

Q
Original author(s) The Q development team at Uppsala University, Sweden
Initial release 1999
Stable release 5.0.6 / 2007
Written in Fortran
Operating system Linux, OS X, Windows by Cygwin, any other Unix variety
Type Molecular dynamics (simulation)
Website xray.bmc.uu.se/~aqwww/q/

Q is a Molecular Dynamics (MD) simulation package which, unlike other MD codes, has specialized since its conception (Marelius et al. 1998) on three specific types of free energy calculations. These calculations are based on the Empirical Valence Bond (EVB) approach, the Free Energy Perturbation (FEP) method, and the Linear Interaction Energy (LIE) method.

The three methods that the program specializes on can return quantitative calculations of the energetic balance which occurs in proteins and nucleic acids. It can provide insight into key problems in biochemistry such as, energetic details on parts of the translation mechanism in mitochondrial ribosomes (Lind et al. 2013), or details in enzymatic reactions (Mones et al. 2013) among others.

The program is similar to gromacs in the sense that it's force-field agnostic, meaning that it does not provide a force-field itself, but it can rather use common force-fields such as CHARMM, AMBER, OPLS, and GROMOS.

The software provides one main utility for molecular dynamics called qdyn, and various subprograms such as qprep (to prepare input files from X-ray coordinates), qfep (to process MD calculations for FEP) and others.

General command to run Q

The general command to run Q is very similar to that of other MD programs and its syntax for a dynamics run is as follows:

   qdyn inputfile.inp > outputfile.out
qdyn 
This is the name of the main program which runs dynamics.
inputfile.inp 
This is text file which specifies all options to the program such as how long the simulation is, how long are the time-steps, what temperature is being simulated and many others.
filename.out 
This is the output file which gives a detailed account of the energetic results. The verbosity of the information in the output file is controlled in the input file. The output places emphasis on reporting on non-bonded interactions such as van der Waals and electrostatic interactions in detail on the solvent, the solute, and the interactions among them.

See also

References

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