ezPES

ezPES is a library of full-dimensional potential energy surfaces (PESs) produced by fitting polynomial representation of PESs to high-level ab initio calculations. We provide a uniform C++ interface to PESs developed at iOpenShell and by other groups. Using this interface, you can integrate PESs into your own program for dynamics or spectroscopy modeling.

To use the PESs, you need to download the precompiled library and a set of parameters for a specific PES. In your code, you first need to initialize the PES by specifying the type of the molecule (number of permutationally equivalent atoms of each type, i.e., multiplicties) and providing a local path to a dierctory with the PES parameters. Once initialized, the value of energy can be computed for a specific values of Cartesian coordinates. Both energies and coordinates are in atomic units.

A sample main program showing how this is done for formaldehyde is given on the right (Click on the image to view a text file containing the program).

Caveats and details:

  1. Only one instance of a PES can be used in a program.
  2. When determining the PES type, first list the largest number of permutationally identically atoms, e.g., for H2CO it is pes_x2y1z1, for C2H3 it is pes_x3y2, etc.
  3. The coordinates are passed as a 1-dimensional array in the following order: a. largest multiplicity first, i.e., for water: H1(x,y,z), H2(x,y,z), O(x,y,z), but for HO2: O1(x,y,z),O2(x,y,z),H(x,y,z) b. If there are several groups of atoms that have the same multiplicity, list these groups by increasing atomic number, e.g., for H2O2: H1(x,y,z), H2(x,y,z), O1(x,y,z), O2(x,y,z) for H2CO: H1(x,y,z), H2(x,y,z), C(x,y,z), O(x,y,z)
  4. The details of algorithm used, fit procedure, level of ab initio data, etc can be found in original publications, which are referenced both here and in a readme file included with each surface.
  5. Included with each surface is a readme file with a few geometries and the energy at each so the user can test whether they are initializing and calling the surface properly.
  6. Please acknowledge ezPES as follows: ezPES library by E. Kamarchik, B. Braams, A.I. Krylov, J.M. Bowman supported by iOpenShell Center (iopenshell.usc.edu); the PES parameters and algorithm are from Ref. [original PES reference as shown below].

Download Linux 32-bit distribution

Download Linux 64-bit distribution

To install, execute:

gzip d < ezpes.v1.0.tar.gz | tar xvf -

and consult README for the compilation instructions

 PES picture Sample code

Download PESs data files (The surfaces in bold are built into the libraries above):

PES Download gzipped tar file Where published
C2H3-radical C2H3-radical.tar.gz J. Chem. Phys. in press (2009)
C3H2-singlet C3H2-singlet.tar.gz J. Chem. Phys. 125, 081101 (2006)
C3H2-triplet C3H2-triplet.tar.gz J. Chem. Phys. 125, 081101 (2006)
H4CF H4CF.tar.gz J. Chem. Phys. 130, 084301 (2009)
HCOH+ HCOH+.tar.gz J. Phys. Chem. A, submitted (2009)
HCOH high energies HCOH-high-energies.tar.gz Unpublished, for a similar PES please see J. Chem. Phys. 128, 204310 (2008)
HCOH low energies HCOH-low-energies.tar.gz J. Chem. Phys. 128, 204310 (2008)
C2H2 C2H2PES-64.tar.gz Chem. Phys. Lett. 368, 421 (2003)
Chem. Phys. Lett. 377, 582 (2003)
CH3OH CH3OHPES-64.tar.gz J. Phys. Chem. A 111, 7317 (2007)
H2CO H2COPES-64.tar.gz J. Phys. Chem. A 108, 8980 (2004)
J. Phys. Chem. A 112, 13267 (2008)
H3O2- H3O2-PES-64.tar.gz J. Am. Chem. Soc. 126, 5042 (2004)
J. Chem. Phys. 123, 064317 (2005)
H3O+ H3O+PES-64.tar.gz J. Chem. Phys. 118, 5431 (2003)
H5O2+ H5O2+PES-64.tar.gz J. Chem. Phys. 122, 044308 (2005)





test_dummy_pes.jpg.gz