libwfa provides a C++ library for the analysis of wavefunctions. This analysis is based on density matrices, which provide a unified formalism independent of the underlying wavefunction model.

The methods which have been implemented are described in detail in Ref. [1] and examples are provided in Ref. [2]. Further developments are covered in Refs [4-7]. Briefly, the implemented methods consist of the following parts:

1. Analysis of state density matrices for
   • population analysis,
   • density plotting,
   • natural orbitals, and
   • analysis of unpaired electrons.
2. Analysis of transition density matrices for
   • plotting of the hole and electron densities,
   • plotting the transition density,
   • natural transition orbitals (NTOs) with a possibility for state-averaging,
   • entanglement analysis based on NTOs [6],
   • electron-hole correlation analysis using the charge transfer numbers (see also Ref. [3]),
   • de-excitation measure.
3. Analysis of difference density matrices for
   • plotting of the attachment/detachment densities,
   • attachment/detachment population analysis, and
   • natural difference orbitals.
4. Real-space analysis of properties within an exciton picture,
   • available for 1TDM and 1DDM see Refs [4], [5].
5. Electrostatic potentials (ESP) of various effective densities [7].

The required input from the quantum chemical program consists of the density matrices of interest, the AO-overlap matrix, the MO coefficients (used for orthogonalization), and information for population analysis. For the exciton analysis routines also the dipole and quadrupole integrals are needed. ESP computation needs access to the two-electron integral engine.

Literature

1. F. Plasser, M. Wormit, A. Dreuw JCP, 2014, 141, 024106 (DOI: 10.1063/1.4885819).
2. F. Plasser, S.A. Baeppler, M. Wormit, A. Dreuw JCP, 2014, 141, 024107 (DOI: 10.1063/1.4885820).
3. F. Plasser, H. Lischka JCTC, 2012, 8, 2777 (DOI: 10.1021/ct300307c).
4. S. Baeppler, F. Plasser, M. Wormit, A. Dreuw PRA, 2014, 90, 052521 (DOI: 10.1103/PhysRevA.90.052521).
5. F. Plasser, B. Thomitzni, S. Baeppler, J. Wenzel, D. Rehn, M. Wormit, A. Dreuw JCC, 2015, 36, 1609-1620 (DOI: 10.1002/jcc.23975).
6. F. Plasser JCP, 2016, 144, 194107 (DOI: 10.1063/1.4949535).
7. P. Kimber, F. Plasser, PCCP 2020, 22, 6058–6080 (DOI: 10.1039/D0CP00369G).

Author

Felix Plasser

Michael Wormit

Stefanie Mewes (Baeppler)

Benjamin Thomitzni

Feng Chen

Anna I. Krylov

Pavel Pokhilko

Date

2014-2021

Copyright

(c) 2014, F. Plasser and M. Wormit

All rights reserved.

Modifications copyright (c) 2019, Loughborough University.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.