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- Yihan Shao, Laszlo Fusti Molnar, +65 authors Martin Head-Gordon
- Physical chemistry chemical physics : PCCP
- 2006

Advances in theory and algorithms for electronic structure calculations must be incorporated into program packages to enable them to become routinely used by the broader chemical community. This work reviews advances made over the past five years or so that constitute the major improvements contained in a new release of the Q-Chem quantum chemistry package,… (More)

- Jing Kong, Christopher A. White, +33 authors John A. Pople
- Journal of Computational Chemistry
- 2000

Q-Chem 2.0 is a new release of an electronic structure program package, capable of performing first principles calculations on the ground and excited states of molecules using both density functional theory and wave function-based methods. A review of the technical features contained within Q-Chem 2.0 is presented. This article contains brief descriptive… (More)

- Martin Head-Gordon, Michael Lee, +7 authors STEVEN R. GWALTNEY

Permission to make digital or hard copies of portions of this work for personal or classroom use is granted provided that the copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise requires prior specific permission by the publisher mentioned above.… (More)

- N Delaney, J Faeder, P E Maslen, R Parson
- 1997

We simulate and interpret the photodissociation and recombination of I 2-embedded in CO 2 clusters using a Hamiltonian that accounts for the strong perturbation of the solute electronic structure by the solvent. The calculated product distributions agree well with the experimental results of Lineberger and co-workers. Excited-state dynamics are more… (More)

- P E Maslen
- The Journal of chemical physics
- 2005

Scaled internal coordinates are introduced for use in the geometry optimization of systems composed of multiple fragments, such as solvated molecules, clusters, and biomolecular complexes. The new coordinates are related to bond lengths, bond angles and torsion angles by geometry-dependent scaling factors. The scaling factors serve to expedite the… (More)

- R Chang, P A Barile, P E Maslen
- The Journal of chemical physics
- 2004

Traditional geometry optimization methods require the gradient of the potential surface, together with a Hessian which is often approximated. Approximation of the Hessian causes difficulties for large, floppy molecules, increasing the number of steps required to reach the minimum. In this article, the costly evaluation of the exact Hessian is avoided by… (More)

- P E Maslen, J M Papanikolas, J Faeder, R Parson, S V Oneil
- 1999

The interaction potentials between the six lowest electronic states of 1, and an arbitrary discrete charge distribution are calculated approximately using a one-electron model. The model potentials are much easier to calculate than ab initio potentials, with the cost of a single energy point scaling linearly with the number of solvent molecules, enabling… (More)

- Yihan Shao, Laszlo Fusti Molnar, +64 authors Martin Head-Gordon
- 2006

Advances in theory and algorithms for electronic structure calculations must be incorporated into program packages to enable them to become routinely used by the broader chemical community. This work reviews advances made over the past five years or so that constitute the major improvements contained in a new release of the Q-Chem quantum chemistry package,… (More)

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