# Citing Octopus

Octopus is a free program, so you have the right to use, change, distribute, and to publish papers with it without citing anyone (for as long as you follow the GPL license). However, the developers of Octopus are also scientists that need citations to bump their CVs. Therefore, we would be very happy if you could cite one or more papers concerning Octopus in your work. The main references are

- Xavier Andrade, David A. Strubbe, Umberto De Giovannini, Ask Hjorth Larsen, Micael J. T. Oliveira, Joseba Alberdi-Rodriguez, Alejandro Varas, Iris Theophilou, Nicole Helbig, Matthieu Verstraete, Lorenzo Stella, Fernando Nogueira, Alán Aspuru-Guzik, Alberto Castro, Miguel A. L. Marques, Ángel Rubio,
*Real-space grids and the Octopus code as tools for the development of new simulation approaches for electronic systems*, arXiV (2015)

- X. Andrade, J. Alberdi-Rodriguez, D. A. Strubbe, M. J. T. Oliveira, F. Nogueira, A. Castro, J. Muguerza, A. Arruabarrena, S. G. Louie, A. Aspuru-Guzik, A. Rubio, and M. A. L. Marques,
*Time-dependent density-functional theory in massively parallel computer architectures: the octopus project*, J. Phys.: Cond. Matt.**24**233202 (2012)

- A. Castro, H. Appel, Micael Oliveira, C.A. Rozzi, X. Andrade, F. Lorenzen, M.A.L. Marques, E.K.U. Gross, and A. Rubio,
*octopus: a tool for the application of time-dependent density functional theory*, Phys. Stat. Sol. B**243**2465-2488 (2006)

- M.A.L. Marques, Alberto Castro, George F. Bertsch, and Angel Rubio,
*octopus: a first-principles tool for excited electron-ion dynamics*, Comput. Phys. Commun.**151**60-78 (2003)

If you use specific functionalities there are other references that you should cite as well.

If you use the linear-response implementation you should cite:

- Xavier Andrade, Silvana Botti, Miguel Marques and Angel Rubio,
*Time-dependent density functional theory scheme for efficient calculations of dynamic (hyper)polarizabilities*, J. Chem. Phys**126**184106 (2007)

If you use the parallel version of the code:

- X. Andrade, J. Alberdi-Rodriguez, D. A. Strubbe, M. J. T. Oliveira, F. Nogueira, A. Castro, J. Muguerza, A. Arruabarrena, S. G. Louie, A. Aspuru-Guzik, A. Rubio, and M. A. L. Marques,
*Time-dependent density-functional theory in massively parallel computer architectures: the octopus project*, J. Phys.: Cond. Matt.**24**233202 (2012)

if you use the GPU implementation:

- X. Andrade and A. Aspuru-Guzik,
*Real-Space Density Functional Theory on Graphical Processing Units: Computational Approach and Comparison to Gaussian Basis Set Methods*, J. Chem. Theo. Comput. (2013)

and if you use more efficient Poisson solvers:

- P. García-Risueño, J. Alberdi-Rodriguez, M. J. T. Oliveira, X. Andrade, M. Pippig, J. Muguerza, A. Arruabarrena, A. Rubio,
*A survey of the parallel performance and accuracy of poisson solvers for electronic structure calculations*, J. Comp. Chem**35**427–444 (2014)

There is also a paper describing the propagation methods used in Octopus:

- A. Castro, M.A.L. Marques, and A. Rubio,
*Propagators for the time-dependent Kohn-Sham equations*, J. Chem. Phys**121**3425-3433 (2004) ,

and a paper about Libxc, the library used by octopus for the exchange-correlation functionals,

- Miguel A. L. Marques, Micael J. T. Oliveira, and Tobias Burnus,
*Libxc: a library of exchange and correlation functionals for density functional theory*, Comput. Phys. Commun., DOI:10.1016/j.cpc.2012.05.007 (2012) OAI: arXiv:1203.1739

Finally, some general references on TDDFT, written by some of us:

*Fundamentals of time-dependent density functional theory*, M.A.L. Marques, N.T. Maitra, F. Nogueira, E.K.U. Gross, and A. Rubio (Eds.), Lecture Notes in Physics, Vol. 837, Springer, Berlin, (2012), ISBN: 978-3-642-23518-4

*Time-dependent density functional theory*, M.A.L. Marques, C. Ullrich, F. Nogueira, A. Rubio, K. Burke, and E.K.U. Gross (Eds.), Lecture Notes in Physics, Vol. 706, Springer, Berlin, (2006), ISBN: 978-3-540-35422-2

- Alberto Castro, M.A.L. Marques, Julio A. Alonso, and Angel Rubio,
*Optical properties of nanostructures from time-dependent density functional theory*, J. Comp. Theoret. Nanoscience**1**231-255 (2004)

- M.A.L. Marques and E.K.U. Gross,
*Time-dependent density functional theory*, Annu. Rev. Phys. Chem.**55**427-455 (2004)

You can find a more extensive list of publications here.