Parallel Quantum Solutions

since 1997

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News

11/14/11

Website/email disruption. On Friday 11/11/11 our 10 year domain name registration expired. As a result we were unreachable via our website or email until Monday 11/14/11. We apologize for any inconvenience.

10/26/11

PQS 4.0 revision 3 is available now. It is a free upgrade for 4.0 users. Please visit the software section to download.

09/13/11

PQS 4.0 revision 2 is available now. It is a free upgrade for 4.0 users. Please visit the software section to download.

09/09/11

PQSMol 2.0 revision 1 is now available for Linux. It is a free upgrade for 2.0 users. The Trial version does not require a license and is free to download.

08/17/11

PQSMol 2.0 is now available for Linux. The Trial version does not require a license and is free to download.

05/17/11

PQS 3.3 users can now get an upgrade to PQS 4.0 for free for 1 year.

REQUEST UPGRADE

SUPPORT

by phone: (CST)
M-F 9:30am - 5:00pm
1-877-759-2777 or
1-479-521-5118.

by email:
general/customer service
sales@pqs-chem.com
technical support
tech@pqs-chem.com

• An efficient vectorized Gaussian integral package allowing high angular momentum basis functions and general contractions.
• Abelian point group symmetry throughout; utilizes full point group symmetry (up to Ih) for geometry optimization step and Hessian (2nd derivative) CPHF.
• Closed-shell (RHF) and open-shell (UHF) SCF energies and gradients, including several initial wavefunction guess options. Improved SCF convergence for open-shell systems.
• Closed-shell (RHF) and open-shell (UHF) density functional energies and gradients including all popular exchange-correlation functionals: VWN, B88, OPTX, LYP, P86, PW91, PBE, B97, HCTH, B3LYP, make up your own functional etc.
• Fast and accurate pure DFT energies and gradients for large basis sets using the Fourier Transform Coulomb (FTC) method.
• Efficient, flexible geometry optimization for all these methods including Baker's Eigenvector Following (EF) algorithm for minimization and saddle-point search, Pulay’s GDIIS algorithm for minimization, use of Cartesian, Z-matrix and delocalized internal coordinates. Includes new coordinates for efficient optimization of molecular clusters and adsorption/reaction on model surfaces.
• Full range of geometrical constraints including fixed distances, planar bends, torsions and out-of-plane bends between any atoms in the molecule and frozen (fixed) atoms. Atoms involved in constraints do not need to be formally bonded and - unlike with a Z matrix - desired constraints do not need to be satisfied in the starting geometry.
• Analytical (and numerical) second derivatives for all these methods, including the calculation of vibrational frequencies, IR intensities, VCD rotational strengths and thermodynamic analysis.
• Efficient NMR Chemical Shifts for closed-shell HF and DFT wavefunctions.
• A full range of effective core potentials (ECPs), both relativistic and non-relativistic, with energies, gradients, analytical second derivatives and NMR.
• Closed-shell MP2 energies and analytical gradients and dual-basis MP2 energies; numerical MP2 second derivatives.
• Potential scan, including scan + optimization of all other degrees of freedom.
• Reaction Path (IRC) following using either Z-matrix, Cartesian or mass-weighted Cartesian coordinates.
• Conductor-like screening solvation model (COSMO) including energies, analytical gradients, numerical second derivatives and NMR.
• Population analysis, including bond orders and atomic valencies (with free valencies for open-shell systems); CHELP and Cioslowski charges.
• Weinhold's Natural Bond Order (NBO) analysis, including natural population and steric analysis.
• Properties module with charge, spin-density and electric field gradient at the nucleus.
• Polarizabilities and dipole and polarizability derivatives; Raman intensities.
• Full Semiempirical package, both open (unrestricted) and closed-shell energies and gradients, including MINDO/3, MNDO, AM1 and PM3. For the latter, all main group elements through the fourth row (except the noble gases) as well as Zinc and Cadmium, have been parametrized.
• Molecular Mechanics using the Sybyl 5.2 and UFF Force Fields.
• QM/MM using the ONIOM method.
• Molecular dynamics using the simple Verlet algorithm.
• Pople-style input for quick input generation and compatibility with other programs.
• Graphical input generation and display
• All major ab initio functionality is fully parallel (except MP2 gradients which is serial only - parallel version under development).

Graphical User Interface to the PQS ab initio program containins a model builder (with two mechanics force fields), job input preparation, serial and parallel job submission (including an interface to SGE, DQS and PBS job queues as well as PVM control) and post-job visualization and display. The latter includes molecular orbitals (cononical, localized and natural), electron densities, electrostatic potentials, optimization history, dynamics trajectories, animation of normal modes and simulation of IR/Raman, NMR and VCD spectra. See a screenshot of PQSMol in action or download a trial verson for Linux or Windows (Linux rpm, tarball, 32-bit and 64-bit versions available on the software page).

The Scaled Quantum Mechanical (SQM) Force Field Module is used for fitting of the calculated results to experimental vibrational spectra. Scale factors can be optimized for best fits to a given set of experimental fundamentals. Precalculated scale factors (for H, C, N, O and Cl) give better agreement with experiment for both vibrational frequencies and IR intensities.