This program carries out the Density Difference Natural Orbital analysis Computed the promotion number, excitation number, and the DDNO's for an excited state calculation
-A. J. Bovill, 2022
The Promotion number was proposed by Martin H. Gordon et al. to find the number of electrons that have been promoted to an excited state. "Analysis of Electronc Transitons as the Difference of Electron Attachment and Detachment Densities" DOI: 10.1021/j100039a012
The Excitation number was an improvement over the promotion number and was proposed by Peter M. W. Gill et al. to represent the number of electrons in the excited state that lie in the unoccupied space of the ground state. "Excitation Number: Characterizing Mutiply Excited States" DOI: 10.1021/acs.jctc.7B00963
The Density Difference Natural Orbital anaylsis in this program is an extension of previous work in our lab involving Natural Ionization Orbitals (NIO') and applied to vertical excitations instead of ionizations. "Natural ionization orbitals for interpreting electron detachment processes" DOI: 10.1063/1.5941738 Previous NIO python code can be found here: https://github.com/hphratchian/nio
This program uses our lab' Merced Quantum chemistry program for working with matrix files produced from gaussian calculations. The OOP format hides away mathematical and works with a number of quantum chemistry codes for easy mathematical interpretation MQC code can be found here: https://github.com/MQCPack/mqcPack