SPEC CPU2006 Benchmark Description

465.tonto

Daniel J. Grimwood <reaper [at] theochem.uwa.edu.au>

Quantum Crystallography

Tonto^{1} is an open source quantum
chemistry package, designed by Dylan Jayatilaka and Daniel J.
Grimwood. Objectives include simplicity and portability; aspects
not seen in many quantum chemistry codes. The code is easily
extendable by chemists with limited programming skills and time,
and is easy to understand and use^{2}.

Tonto is written within an object oriented design, in Fortran 95. It uses derived types and modules to represent classes. Classes range from integers and text files, through to atoms, spacegroups and molecules. There is a "self" variable in most routines, which should be familiar from many OO languages. Tonto uses dynamic memory instead of common blocks, and uses array operations where possible.

The profiles of Tonto calculations are typical of many *ab
initio* quantum chemistry packages. That is, a large portion is
dedicated to the evaluation of integrals between products of
Gaussian basis functions.

The SPEC reference calculation is in the field of quantum
crystallography. It places a constraint on a molecular Hartree-Fock
wavefunction calculation to better match experimental X-ray
diffraction data^{3}. It is expected
that other similar properties calculated from the constrained
wavefunction should also agree better with experiment.

The input file contains the crystal structure, atom positions,
and basis functions, and experimental X-ray diffraction data. It
then gives calculation parameters, and does the calculation. The
crystal structure, atom positions, and X-ray data are from the
literature^{4}.

The main output file is regularly updated to show how far the
calculation is from the final answer. Once the final model
wavefunction is obtained, the X-ray diffraction data calculated
from it are printed out together with the experimental data and
compared. The chi^{2} of one means the calculated and
experimental data sets agree to within experimental accuracy.

The coefficients for the wavefunction are stored in the file
"n2o4.molecular_orbitals,restricted,ascii". Although not done so in
the 465.tonto reference calculation, this data can then be used to
calculate other properties of the system, such as the Electron
Localisation Function or the electrostatic potential^{5}.

Fortran 95

Tonto makes extensive use of new features added to the Fortran language with the Fortran 90/95 standards (such as generic interfaces and vector subscripts). Some older compilers may not have complete support for these features; therefore, users may wish to obtain the most recent update of their compiler before trying Tonto.

- 1 Tonto home page - http://www.theochem.uwa.edu.au/tonto/
- 2 D. Jayatilaka and D. J.
Grimwood,
*Computational Science - ICCS 2003*,**2660**, 142-151, (2003) - 3 D. Jayatilaka and D. J.
Grimwood,
*Acta Cryst.*, A**57**, 76-86, (2001) - 4 M. Messerschmidt, A. Wagner, M.
W. Wong and P. Luger,
*J. Am. Chem. Soc.*,**124(5)**, 732-733, (2002) - 5 D. J. Grimwood, I. Bytheway and
D. Jayatilaka,
*J. Comp. Chem.*,**24(4)**, 470-483, (2003)

Last updated: $Date: 2011-08-16 18:23:17 -0400 (Tue, 16 Aug 2011) $