ezMode is a vibrational structure code which is capable of performing vibrational self-consistent field (VSCF), vibrational configuration interaction (VCI), and reaction path Hamiltonian (RPH-VCI) calculations. It is designed to easily interface with ezPES based potentials, however it also contains routines that enable running it with user-defined surfaces. The code is based on the Waston Hamiltonian for non-linear molecules and the potential is represented as an expansion in coupled modes.

Features of this program include the ability to calculate vibrational wave functions and excitation energies, 1- and 2-mode density matrices, transition dipole moments and infrared intensities (when coupled with a dipole moment surface), expectation values of 1- and 2-mode operators, and vibrationally averaged rotational constants.

The ezMode source code is freely available under GNU license and may be downloaded below.

The theoretical background is described in:

J. M. Bowman, T. Carrington, and H.-D. Meyer, Mol. Phys. 106, 2145 (2008). [VCI/n-mode representation]
J. M. Bowman, J. Chem. Phys. 68, 608 (1978). [VSCF]
J. K. G. Watson, Mol. Phys. 15, 479 (1968). [Watson Hamiltonian]
W. H. Miller, N. C. Handy, and J. E. Adams. 72, 99 (1980). [RPH]

The code was used in the following publications:

E. Kamarchik, Y. Wang, J. M. Bowman "Quantum vibrational analysis and infrared spectra of microhydrated sodium ions using an ab initio potential", J. Chem. Phys., 134, 114311 (2011)
E. Kamarchik and J. M. Bowman "Quantum Vibrational Analysis of Hydrated Ions Using an ab Initio Potential", J. Phys. Chem. A, 114, 12945 (2010)
E. Kamarchik, O. Kostko, J. M. Bowman, et al. "Spectroscopic signatures of proton transfer dynamics in the water dimer cation", J. Chem Phys., 132, 194311 (2010)

Download ezMode: ezMode.tar.gz (includes a sample input)

Download manual: ezMode_User_Guide.pdf

To acknowledge ezMode, use the following citation:
E. Kamarchik, J.M Bowman, and A.I. Krylov, ezMode, http://iopenshell.usc.edu/downloads/ezmode

Please also acknowledge iOpenShell:
"This work was conducted using the resources of the iOpenShell Center for Computational Studies of Electronic Structure and Spectroscopy of Open-Shell and Electronically Excited Species (http://iopenshell.usc.edu) supported by the National Science Foundation through the CRIF:CRF program."