A misprint was found in the last digit of the parameter C 0 of Table II. The correct value is C 0 0:057 238 4. Moreover, to reobtain exactly Fig. 3, one has to use G 0 0:339 97 (not G 0 0:34 as originally printed). The use of the misprinted values of C 0 and G 0 which appear in the original version of Table II does not affect the results for r s & 30; it does, instead, shift the Wigner crystallization to slightly larger r s .Finally, the text following Eq.(3) has two rather obvious misprints: the factors of 2 and 24 instead of 1=2 and 1=24 in the definitions of 1 and 2 . This is completely harmless: all results and equations of the Letter are based on the correct definition, not on the misprinted one.

We compute the electron-phonon coupling ͑EPC͒ of selected phonon modes in graphene and graphite using various ab initio methods. The inclusion of nonlocal exchange-correlation effects within the GW approach strongly renormalizes the square EPC of the A 1 Ј K mode by almost 80% with respect to density-functional theory in the LDA and GGA approximations. Within GW, the phonon slope of the A 1 Ј K mode is almost two times larger than in GGA and LDA, in agreement with phonon dispersions from inelastic x-ray scattering and Raman spectroscopy. The hybrid B3LYP functional overestimates the EPC at K by about 30%. Within the Hartree-Fock approximation, the graphene structure displays an instability under a distortion following the A 1 Ј phonon at K. The electron-phonon coupling ͑EPC͒ is one of the fundamental quantities in condensed matter. It determines phonon dispersions and Kohn anomalies, phonon-mediated superconductivity, electrical resistivity, Jahn-Teller distortions, etc. Nowadays, density-functional theory ͑DFT͒ within local and semilocal approximations is considered the "standard model" to compute ab initio the electron-phonon interaction and phonon dispersions.1 Thus, a failure of DFT would have major consequences in a broad context. In GGA and LDA approximations, 2 the electron exchange-correlation energy is a local functional of the charge density, and the long-range character of the electron-electron interaction is neglected. These effects are taken into account by Green's-function approaches based on the screened electron-electron interaction W such as the GW method.3 GW is considered the most precise ab initio approach to determine electronic bands, but so far it has never been used to compute EPCs nor phonon dispersions. The semiempirical B3LYP functional 2 partially includes long-range Hartree-Fock ͑HF͒ exchange. B3LYP has been used to compute phonon frequencies but, so far, not the EPC.The EPC is a key quantity for graphene, graphite, and carbon nanotubes. It determines the Raman spectrum, which is the most common characterization technique for graphene and nanotubes 4,5 and the high-bias electron transport in nanotubes.6 Graphene and graphite are quite unique systems in which the actual value of the EPC for some phonons can be obtained almost directly from measurements. In particular, the square of the EPC of the highest optical-phonon branch ͑HOB͒ at the symmetry K point is proportional to the HOB slope near K. 7 The HOB K slope can be measured by inelastic x-ray scattering ͑IXS͒ 8,9 or by the dispersion of the D and 2D lines as a function of the excitation energy in a Raman experiment. 5,[10][11][12][13] A careful look at the most recent data suggests that the experimental phonon slopes ͑and thus the EPC͒ are underestimated by DFT. 5 The ability of DFT ͑LDA and GGA͒ in describing the EPC of graphene was also questioned by a recent theoretical work.14 Here, we show that: ͑i͒ the GW approach, which provides the most accurate ab initio treatment of electron correlation, can be used to compute the elect...

yambo is an open source project aimed at studying excited state properties of condensed matter systems from first principles using many-body methods. As input, yambo requires ground state electronic structure data as computed by density functional theory codes such as Quantum ESPRESSO and Abinit. yambo's capabilities include the calculation of linear response quantities (both independentparticle and including electron-hole interactions), quasi-particle corrections based on the GW formalism, optical absorption, and other spectroscopic quantities. Here we describe recent developments ranging from the inclusion of important but oft-neglected physical effects such as electron-phonon interactions to the implementation of a real-time propagation scheme for simulating linear and nonlinear optical properties. Improvements to numerical algorithms and the user interface are outlined. Particular emphasis is given to the new and efficient parallel structure that makes it possible to exploit modern high performance computing architectures. Finally, we demonstrate the possibility to automate workflows by interfacing with the yambopy and AiiDA software tools. CONTENTS