This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. We also thank CSC — IT Center for Science (Finland) for computational resources. We acknowledge financial support by ASI Grant 2016-24-H.0 and Academy of Finland grant 295113. This work has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement number 687312. CJM is supported by an FCT Research Professorship, contract reference IF/00064/2012, funded by FCT/MCTES (Portugal) and POPH/FSE (EC). JGN acknowledges financial support from the Spanish MINECO for a ‘Ramon y Cajal’ fellowship (RYC-2013-13256) and the I+D 2015 project AYA2015-65887-P (MINECO/FEDER). GR acknowledges support from the National Research Foundation of Korea (NRF) through Grant No. 2017R1E1A1A01077508 funded by the Korean Ministry of Education, Science and Technology (MoEST), and from the faculty research fund of Sejong University in 2018. We thank Jean Kaplan for useful comments on the manuscript.