The iDEA code (interacting Dynamic Electrons Approach) is a Python software suite (with Cython extensions) developed in Rex Godby's group at the University of York since 2010. It has a central role in a number of research projects related to multi-particle quantum mechanics for electrons in matter.

iDEA's main features are:

- Exact solution of the many-particle time-independent Schrödinger equation, including exact exchange and correlation
- Exact solution of the many-particle time-dependent Schrödinger equation, including exact exchange and correlation
- Simplicity achieved using spinless (yet fermionic) electrons in one dimension
- An arbitrary external potential that may be time-dependent
- Robust optimisation methods to determine the exact DFT/TDDFT* Kohn-Sham potential and energy components
- Implementation of various approximate functionals (established and novel) for comparison
- Established and novel localisation measures
- Exact excited states and linear-response functions
- Many-body perturbation theory (at various levels)

iDEA code contributors (listed alphabetically): Sean Adamson, Jacob Chapman, Thomas Durrant, Razak Elmaslmane, Mike Entwistle, Rex Godby, Matt Hodgson, Piers Lillystone, Aaron Long, Robbie Oliver, James Ramsden, Ewan Richardson, Matthew Smith, Leopold Talirz and Jack Wetherell.

Video introductions to the iDEA code, by Jack Wetherell and Matt Hodgson respectively.

Page updated February 2021

1. "Exact time-dependent density-functional potentials for strongly correlated tunneling electrons", M.J.P. Hodgson, J.D. Ramsden, J.B.J. Chapman, P. Lillystone, and R.W. Godby, Physical Review B (Rapid Communications) ** 88** 241102(R) (2013). Further information

2. "Role of electron localization in density functionals", M.J.P. Hodgson, J.D. Ramsden, T.R. Durrant and R.W. Godby, Physical Review B (Rapid Communications) **90** 241107(R) (2014). Further information

3. "Origin of static and dynamic steps in exact Kohn-Sham potentials", M.J.P. Hodgson, J.D. Ramsden and R.W. Godby, Physical Review B **93** 155146 (2016) (Editors' Suggestion). Further information

4. "Local density approximations from finite systems", M.T. Entwistle, M.J.P. Hodgson, J. Wetherell, B. Longstaff, J.D. Ramsden and R.W. Godby, Physical Review B **94** 205134 (2016). Further information

5. "How Interatomic Steps in the Exact Kohn–Sham Potential Relate to Derivative Discontinuities of the Energy", M.J.P. Hodgson, Eli Kraisler, Axel Schild and E.K.U. Gross,
Journal of Physical Chemistry Letters **8** 5974–5980 (2017). Further information Accompanying video by Matt Hodgson

6. "Electron localisation in static and time-dependent one-dimensional model systems", T.R. Durrant, M.J.P. Hodgson, J.D. Ramsden and R.W. Godby,
Journal of Physics: Condensed Matter **30** 065901 (2018). Further information

7. "*GW* self-screening error and its correction using a local density functional", J. Wetherell, M.J.P. Hodgson and R.W. Godby, Physical Review B (Rapid Communications) **97** 121102(R) (2018).
Further information

8. "Measuring adiabaticity in non-equilibrium quantum systems", A.H. Skelt, R.W. Godby and I. D'Amico,
Physical Review A **98** 012104 (2018).
Further information

9. "Metrics for two electron random potential systems", A.H. Skelt, R.W. Godby and I. D'Amico,
Brazilian Journal of Physics **48** 467–471 (2018).
Further information

10. "Accuracy of electron densities obtained via Koopmans-compliant hybrid functionals",
A.R. Elmaslmane, J. Wetherell, M.J.P. Hodgson, K.P. McKenna and R.W. Godby,
Physical Review Materials **2** 040801(R) (Rapid Communications) (2018).
Further information

11. "Comparison of local density functionals based on electron gas and finite systems",
M.T. Entwistle, M. Casula and R.W. Godby,
Physical Review B **97** 235143 (2018).
Further information

12. "Advantageous nearsightedness of many-body perturbation theory contrasted with Kohn-Sham density functional theory",
J. Wetherell, M.J.P. Hodgson, L. Talirz and R.W. Godby,
Physical Review B **99** 045129 (2019).
Further information
Accompanying video by Jack Wetherell

13. "Exact exchange-correlation kernels for optical spectra of model systems",
M.T. Entwistle and R.W. Godby,
Physical Review B (Rapid Communications) **99** 161102(R) (2019).
Further information

14. "Accurate real-time evolution of electron densities and ground-state properties from generalized Kohn-Sham theory",
M.J.P. Hodgson and J. Wetherell, Physical Review A **101** 032502 (2020).
Further information Accompanying video by Matt Hodgson

15. "Exact non-adiabatic part of the Kohn-Sham potential and its fluidic approximation",
M.T. Entwistle and R.W. Godby, Physical Review Materials **4** 035002 (2020).
Further information

16. "Insights into one-body density matrices using deep learning",
Jack Wetherell, Andrea Costamagna, Matteo Gatti and Lucia Reining, Faraday Discussions **224** 126 (2020).
Further information

17. "From Kohn-Sham to many-electron energies via step structures in the exchange-correlation potential",
Eli Kraisler, M.J.P. Hodgson and E.K.U. Gross, Journal of Chemical Theory and Computation **17** 1390 (2021).
Further information

18. "Exact exchange-correlation potentials for calculating the fundamental gap with a fixed number of electrons",
M.J.P. Hodgson, J. Wetherell and Emmanuel Fromager, Physical Review A **103** 012806 (2021).
Further information

19. "Insights from exact exchange-correlation kernels",
N.D. Woods, M.T. Entwistle and R.W. Godby, Physical Review B **103** 125155 (2021).
Further information

20. "Exact expressions for the height of the interatomic step in the exchange-correlation potential from the derivative discontinuity of the energy", M.J.P. Hodgson, arXiv (2021). Further information

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