Settore scientifico disciplinare di riferimento | (FIS/03) |

Ateneo | Università degli Studi di ROMA "La Sapienza" |

Struttura di afferenza | Dipartimento di FISICA |

Recapiti | Elenco recapiti telefonici |

January 14, 1967

EMPLOYMENT SUMMARY

Nov. 2015 - ..., Professore Ordinario, Università di Roma la Sapienza

Oct. 2015 - ..., Fellow of the American Physical Society

Jul. 2012 - Oct. 2015, Directeur de recherche at the CNRS

Sep. 2001 - ..., Member of the “Institut Universitaire de France"

Sep. 1998 - Jun. 2012, Professeur d'Universitè, Universitè Pierre et Marie Curie, Paris

Jan. 1997 - Aug. 1998, Maître assistant, IRRMA, Universitè de Geneva

Nov. 1994 - Dec. 1996, Miller Research Fellow, University of California at Berkeley

EDUCATION

Oct. 1990 - Oct. 1994, Doctoral studies: Universitè de Geneva and SISSA Trieste

Oct. 1985 - Jul. 1990, Undergraduate studies: Università di Pisa and Scuola Normale Superiore

PUBLICATIONS

ResearcherID: K-5726-2012

http://www.researcherid.com/rid/K-5726-2012

224 publications on ISI web of science that include:

34 Phys. Rev. Lett.

1 Science

2 Nature Materials

1 Nature Physics

2 Nature Comm.

7 J. Am. Chem. Soc.

3 Nano Lett.

72 Phys. Rev. B.

Total number of citations: 20267

H-index (Hirsch): 56

Number of papers with more than 100 citations: 31

RESEARCH ACHIEVEMENTS

My activity focuses on the prediction of the physical properties of complex materials using first-principles electronic structure methods, and the development of original conceptual developments, methods, and algorithms to treat interacting electrons.

-Simulation of spectroscopies

I have given particular emphasis to collaboration with experimental groups in very diverse fields, and to the use of ab-initio calculations to predict and interpret spectroscopic data. I have pioneered several original developments in this field especially for magnetic spectroscopies in extended systems and applied all these methods extensively, with e.g. many recent notable applications in vibrational spectroscopies for carbon nanotubes and graphene. I developed the first theory for the first-principles calculation of NMR/EPR parameters in solids. Previous methods could deal only with finite systems. Our new theory has been implemented in two codes, Quantum Espresso and Castep-NMR, that are nowadays widely used within the experimental community of solid-state NMR. I have been working in collaboration with several experimental NMR groups to use the NMR codes for the interpretation of NMR spectra in silicate crystals and glasses, in zeolites, in biomolecular crystals, water, minerals, and in boron-rich materials. I have also developed methods and codes for the efficient simulation of Raman, IR and Xanes spectra, for the non-linear electrical susceptibility, the magnetic susceptibility, and the orbital magnetization. I identified very large non-adiabatic effects (crucial to interpret experimental data) in the Raman spectra of carbon-nanotubes, graphene and, more in general, in layered metals.

-Phonon-mediated superconductivity

The coupling of phonons with electrons is another important topic of my research. I studied several phonon mediated superconductors, identifying the most relevant phonons and and electron-phonon interactions. I studied the origin of superconductivity-variation in Te under pressure. In MgB2, I extracted from experimental inelastic X-ray scattering data, the electron-phonon coupling parameters. I studied the effects of magnetism and doping on the electron-phonon coupling in BaFe2As2. I suggested that highly doped diamond (BC5) and hole-doped icosahedral Boron compounds are potential candidates for high Tc superconductivity. I identified and characterized the electron-phonon coupling responsible for superconductivity in CaC6, KC8 and in other intercalated graphite, the charge-Density Wave and Superconducting Dome in TiSe2, the intercalant and intermolecular phonon assisted superconductivity in K-doped picene, the inverse isotope effect in superconducting palladium-hydrates. I have proposed that phonon-mediated superconductivity can be induced in graphene by coating it with metal ions. I studied the electron-phonon interaction and the important role of anharmonicity in H3S at high pressure, the superconductor with the highest Tc (203 K) so far measured. For the description of the electron dispersion and of the electron-phonon interaction I have implemented an approach that takes advantage of the localization in real space of the electronic Wannier-function. Such model has the computational complexity of a TB Hamiltonian but retains the accuracy of the DFT ab-initio calculations. In graphene I demonstrated how the e-e interaction and the electron doping modulate the electron-phonon interaction.

-Carbon nanotubes and graphene

I explained theoretically (in the most cited PRL of 2006) the origin of the characteristic feature of graphene Raman spectra that is currently used to count the number of layers present in a graphene sample. This technique is nowadays used in most experimental papers to identify monolayer and bilayer graphene. I predicted (anticipating a subsequent experimental confirmation) that Raman can also be used to measure the doping level of graphene and carbon nanotubes. I predicted and identified, in experimental data, the presence of significant Kohn anomalies in the phonon dispersion of carbon nanotubes, graphite and graphene. I used these Kohn anomalies, together with the Raman and IR lifetimes and temperature-shifts, to obtain, from experiments, accurate values of the electron-phonon and phonon-phonon coupling of graphite based materials. I showed that in graphene and graphite DFT is not able to correctly account for the experimentally observed electron-phonon interaction and one need to include electron-correlation effects at the GW level. The detailed knowledge of the electron-phonon and phonon-phonon interaction parameters has allowed me to study the origin of current saturation in graphene and in metallic nanotubes at high field. In metallic nanotubes I showed that the decrease of the differential conductance at high field is due to the presence of hot phonons. I proposed to use isotope-enriched nanotubes to control the temperature of such hot phonons and to boost the electrical conductance of metallic tubes. Finally, a key step in the use of graphene in electronics is the possibility to cut atomically at and defected-free edges. With this goal I used first-principles DFT calculations to identify the most stable regular edged of graphene under different chemical environments.

-Anharmonicity, phonon-phonon interaction, CDW and thermal conduction

I developed a Monte-Carlo type of approach to treat, with ab-initio methods strong anharmonic systems beyond perturbation theory, using the Self-consistent Harmonic approximation. I am now using the method to describe temperature dependent phonons (and phonon properties) in CDW materials (NbSe2, NbS2), ferroelectrics, and thermo-electrics and H-based superconductors. When anharmonicity can be treated as perturbation, the leading term is the three-phonon scattering coefficient, which is given by the third-order derivative of the energy with respect to atomic displacements (V(3)). I developed a code to compute V(3). I also developed a new method to compute the thermal conductivity solving the Boltzmann transport equation taking advantage of a variational principle. I published a paper on diamond and I am now working of the thermal transport properties of 2D materials.

-Amorphous materials

I used the possibility of simulating NMR and Raman data to elucidate the local geometry and the medium range order in many dis-ordered system, including amorphous allumino-silicate glasses, silica, amorphous boron-oxides, amorphous carbon.

-Mineral-physics and geochemistry

I have also worked at the interface between solid-state physics and geology. I used DFT calculations to interpret the IR spectra of many natural minerals (especially clay minerals) including multiwall asbestos nanotubes. I showed that it is possible to use ab-initio calculation to compute accurate isotope equilibrium fractionation, one of the most important geological indicators (a properties determined by the quantum motion of the nuclei), among minerals and with liquid water.