\section{Acknowledgments}

We would like to thank all the people that have contributed to Octopus and to the development and implementation of the applications presented in this article. In particular we would like to acknowledge Pablo Garcia-Risue\~no (for his contrbution to the development of scalable Poisson solvers), Joaquim Jornet Somoza, Silvana Botti, Jacob Sanders, Johanna Fuks, Arto Sakko, Heiko Appel, Danilo Nitsche, Florian Lorenzen, Daniele Varsano, Carlo A. Rozzi, Alain Delgado, Pablo Garcia-Gonz\'alez, Javier Muguerza, and Agustin Arruabarrena.

XA acknowledges that part of this work was performed under the auspices of the U.S. Department of Energy at Lawrence Livermore National Laboratory under Contract DE-AC52-07A27344. XA and AA-G would like to thank the support received from Nvidia Corporation through the CUDA Center of Excellence program and the US Defense Threat Reduction Agency under contract no. HDTRA1-10-1-0046. DAS acknowledges support from the U.S. National Science Foundation graduate research program and IGERT fellowships, and from ARPA-E under grant DE-AR0000180. MJTO acknowledges financial support from the Belgian FNRS through FRFC project number 2.4545.12 ``Control of attosecond dynamics: applications to molecular reactivity''.
NH and IT received support from a Emmy-Noether grant from Deutsche Forschungsgemeinschaft.
JAR, AV, UDG, AHL and AR ackowledge financial support by the European Research Council Advanced Grant DYNamo (ERC-2010- AdG-267374), European Commission project CRONOS (Grant number 280879-2 CRONOS CP-FP7), Marie Curie ITN POCAONTAS (FP7-PEOPLE-2012-ITN, project number 316633), OST Actions CM1204 (XLIC), and MP1306 (EUSpec), Spanish Grant (FIS2013-46159-C3-1-P) and Grupo Consolidado UPV/EHU del Gobierno Vasco (IT578-13). JAR acknowledges the Department of Education, Universities and Research of the Basque Government (grant IT395-10).
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