Andrea Corso

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Papers by Andrea Corso

Magnetism of Fe double wires deposited on Ir(100)

Bulk bcc Fe is a prototypical ferromagnet (FM), but a single monolayer of Fe on W(001) has been k... more Bulk bcc Fe is a prototypical ferromagnet (FM), but a single monolayer of Fe on W(001) has been known to be antiferromagnetic (AFM). Very recent spin-polarized STM experiments on Fe double chains deposited on Ir(100) 5x1 [1] showed that these adsorbed nanowires are AFM too [2]. We study the magnetic properties of this system using ab-initio density functional theory and

Magnetic phenomena, spin-orbit effects, and Landauer conductance in Pt nanowire contacts

Platinum monatomic nanowires were predicted to spontaneously develop magnetism, involving a sizab... more Platinum monatomic nanowires were predicted to spontaneously develop magnetism, involving a sizable orbital moment via spin orbit coupling, and a colossal magnetic anisotropy. We present here a fully-relativistic (spin-orbit coupling included) pseudo-potential density functional calculation of electronic and magnetic properties, and of Landauer ballistic conductance of Pt model nanocontacts consisting of short nanowire segments suspended between Pt leads or tips,

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Coulomb couplings in positively charged fullerene

Philosophical Magazine Part B, 2002

We compute, based on density-functional electronic-structure calculations, the Coulomb couplings ... more We compute, based on density-functional electronic-structure calculations, the Coulomb couplings in the hu highest occupied orbital of molecular C60. We obtain a multiplet-averaged Hubbard U ≈ 3 eV, and four Hund-rule-like intramolecular multiplet-splitting terms, each of the order of a few hundred millielectronvolts. According to these couplings, all C 60 ions should possess a high-spin ground state if kept in

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Ab initio ballistic conductance with spin-orbit coupling: Application to monoatomic wires

Physical Review B, 2006

The approach proposed by Choi and Ihm [Phys. Rev. B 59, 2267 (1999)] for calculating the ballisti... more The approach proposed by Choi and Ihm [Phys. Rev. B 59, 2267 (1999)] for calculating the ballistic conductance of open quantum systems within the Landauer-Büttiker approach is generalized to fully relativistic ultrasoft pseudopotentials, enabling it to deal with ballistic transport in the presence of spin-orbit coupling. As a test case, we present the complex k -vector electronic structure of a

Monatomic Au wire with a magnetic Ni impurity: Electronic structure and ballistic conductance

Physical Review B, 2008

The influence of a magnetic impurity (Ni atom) on the electronic, magnetic, and Landauer conducta... more The influence of a magnetic impurity (Ni atom) on the electronic, magnetic, and Landauer conductance properties of a monatomic Au wire is studied by first-principles density-functional calculations. We compare two adsorption geometries: bridge and substitutional. We find that the Ni atom remains magnetic in both cases; however, in the bridge geometry, the total spin is close to 1/2 and the

Microscopic structure of the substitutional Al defect in α quartz

Physical Review B, 2000

First-principles pseudopotential calculations are reported for the lattice distortion and electro... more

Magnetism-induced ballistic conductance changes in palladium nanocontacts

European Physical Journal B, 2010

We present first-principles calculations of the effects of magnetism on the ballistic conductance... more We present first-principles calculations of the effects of magnetism on the ballistic conductance of a model Pd nanocontact, made of a short Pd monatomic stretched chain placed between two Pd leads, simulated by semi-infinite (100) slabs. The stretching makes the suspended Pd chain generally ferromagnetic. The spin-resolved ballistic conductance, calculated according to the Landauer-Büttiker formula is found to be 0.85G0

Electron-vibration coupling constants in positively charged fullerene

Philosophical Magazine Part B, 2001

Recent experiments have shown that C 60 can be positively field-doped. In that state, fullerene e... more Recent experiments have shown that C 60 can be positively field-doped. In that state, fullerene exhibits a higher resistivity and a higher superconducting temperature than the corresponding negatively doped state. A strong intramolecular hole-phonon coupling, connected with the Jahn-Teller effect of the isolated positive ion, is expected to be important for both properties, but the actual coupling strengths are so far unknown. Based on density functional calculations, we determine the linear couplings of the two a g , six g g , and eight h g vibrational modes to the H u HOMO level of the C 60 molecule. The couplings predict a D 5 distortion, and an H u vibronic ground state for C + 60 . They are also used to generate the dimensionless coupling constant λ which controls the superconductivity and the phonon contribution to the electrical resistivity in the crystalline phase. We find that λ is 1.4 times larger in positively-charged C 60 than in the negatively-doped case. These results are discussed in the context of the available transport data and superconducting temperatures. The role of higher orbital degeneracy in superconductivity is also addressed. *

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Wannier and Bloch orbital computation of the nonlinear susceptibility

Physical Review B, 1994

We present a method to compute high-order derivatives of the total energy of a periodic solid wit... more

Structural, electronic, and magnetic properties of Fe2SiO4 fayalite: Comparison of LDA and GGA results

Physical Review B, 2003

Adsorption configurations for a series of transition metal (TM) 3d atoms adsorbed on the zigzag (... more Adsorption configurations for a series of transition metal (TM) 3d atoms adsorbed on the zigzag (8, 0) BNNT at five different sites have been investigated using the first-principles PAW potential within DFT under GGA. The most stable adsorption sites are different for different TM atoms. Partially filled 3d metals V, Cr and Mn can bind strongly with zigzag (8, 0) BNNT, and Sc, Ti, Co and Ni can be chemically adsorbed on the (8, 0) BNNT. The binding between the Fe or Cu atom and the BNNT is only marginal. One unusual case is Zn. Its zero binding energy independent of the adsorption sites implies it can only physically adsorbed on the BNNT mainly stemmed from the van de Waals interaction. Electronic structure analyses show that: (1) for each TM atom adsorbed at five different sites, the total DOS curves of both majority and minority spins make a slightly relative shift along the energy axis, and for each site the total DOS of the minority spin shifts slightly in high energy direction with respect to that of the majority spin lead to a exchange splitting, except fully filled 3d metals Cu and Zn; (2) total DOS curves of both the majority and minority spins for the adsorbed systems shift to the lower energy region compared with that of the pristine (8, 0) BNNT. And the smaller 3d electrons number of the TM atom, the larger shift to the lower energy region of its DOS curves; (3) for V-, Mn-and Fe-adsorbed (8, 0) BNNT, only one type of electrons (either majority spin or minority spin) passes through the Fermi level implies these adsorbed systems are all half-metals.

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Ab initio study of piezoelectricity and spontaneous polarization in ZnO

Physical Review B, 1994

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Density-functional perturbation theory for lattice dynamics with ultrasoft pseudopotentials

Physical Review B, 1997

We generalize density-functional perturbation theory for lattice dynamics to Vanderbilt's ultraso... more We generalize density-functional perturbation theory for lattice dynamics to Vanderbilt's ultrasoft pseudopotential scheme. This formulation accounts for the nonorthogonality of the orbitals, the augmentation of the electron density, and the dependence of the generalized orthogonality constraint on the atomic positions. Both insulating and metallic systems are considered. Application of the theory to the vibrations of small molecules ͑CO, CO 2 , CH 4 , and H 2 O͒ and to the phonon dispersion of the noble metals ͑Cu, Ag, Au͒ shows overall agreement with experiment. ͓S0163-1829͑97͒51742-5͔

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Generalized gradient approximations to density functional theory: comparison with exact results

Theoretical and Computational Chemistry, 1996

Pseudopotential calculations within density-functional theory for a few selected solids ͑Si, GaAs... more Pseudopotential calculations within density-functional theory for a few selected solids ͑Si, GaAs, and Al͒ are used to assess the validity of two generalized-gradient approximations ͑GGA's͒, the one proposed by Becke and Perdew ͑BP͒ and the more recent one proposed by Perdew and Wang ͑PW͒ in comparison with the currently used local-density approximation ͑LDA͒. The GGA's give total energies of atoms and cohesive energies of solids that are closer to experiment than the LDA results. Lattice constants are reproduced with the same accuracy as in LDA, while bulk moduli and zone-center phonon frequencies are underestimated with respect to both the LDA and the experimental values. Comparison to all-electron results shows that in both GGA schemes the validity of the pseudopotential approach is as good as in LDA. The predictions of the two GGA's are similar, the PW functional yielding results marginally, but systematically, closer to experiment. The calculated values of the transition pressure in Si between the diamond and the ␤-tin structure are 72 kbar ͑LDA͒, 164 kbar ͑BP͒, and 135 kbar ͑PW͒, to be compared with the two available experimental values of 103 and 125 kbar.

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Ab initio study of the dielectric properties of silicon and gallium arsenide using polarized Wannier functions

Physical Review B, 1998

We present a first-principles calculation of the electronic properties of crystalline silicon and... more We present a first-principles calculation of the electronic properties of crystalline silicon and gallium arsenide in a uniform electric field. Polarized Wannier-like functions which are confined in a finite region are obtained by minimizing a total-energy functional which depends explicitly on the macroscopic polarization of the solid. The polarization charge density and the electronic dielectric constant are computed via finite differences. The results coincide with those of the linear response approach in the limit of vanishing electric field and infinite localization region.

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Density-functional theory of the nonlinear optical susceptibility: Application to cubic semiconductors

Physical Review B, 1996

We present a general scheme for the computation of the time dependent (TD) quadratic susceptibili... more We present a general scheme for the computation of the time dependent (TD) quadratic susceptibility (χ (2) ) of an extended insulator obtained by applying the '2n + 1' theorem to the action functional as defined in TD density functional theory. The resulting expression for χ (2) includes self-consistent

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Atomic Structure and Vibrational Properties of Icosahedral B4C Boron Carbide

Physical Review Letters, 1999

The atomic structure of icosahedral B4C boron carbide is determined by comparing existing infrare... more The atomic structure of icosahedral B4C boron carbide is determined by comparing existing infrared absorption and Raman diffusion measurements with the predictions of accurate ab initio lattice-dynamical calculations performed for different structural models, a task presently beyond x-ray and neutron diffraction ability. By examining the inter- and intraicosahedral contributions to the stiffness we show that, contrary to recent conjectures, intraicosahedral

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Nonlinear piezoelectricity in CdTe

Physical Review B, 1993

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Ab initio phonon dispersions of Fe and Ni

Physical Review B, 2000

We present the ab initio phonon dispersions of magnetic bcc Fe and fcc Ni. Our calculations are c... more

Adsorption of ethylene on stepped Ag() surfaces

by Andrea Corso and Stefano de Gironcoli

Surface Science, 2004

The adsorption of ethylene on stepped Ag(n 1 0), n ¼ 2; 3; 4, surfaces has been studied and chara... more The adsorption of ethylene on stepped Ag(n 1 0), n ¼ 2; 3; 4, surfaces has been studied and characterised using density-functional theory. We find that ethylene prefers to adsorb on the on-top sites of the step edge, the corresponding binding energy being practically insensitive to the molecular orientation with respect to the C-C axis rotation around the surface normal. The (1 0 0) terraces were found to behave similarly to the flat Ag(1 0 0) surface which binds ethylene only very weakly.

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Raman scattering intensities in α-quartz: A first-principles investigation

Physical Review B, 2001

Using a first-principles density functional approach, we calculate the first-order Raman intensit... more Using a first-principles density functional approach, we calculate the first-order Raman intensities of ␣-quartz. The dynamical charge tensors, vibrational frequencies and eigenmodes, and polarizability tensors are obtained within a perturbational approach. We calculate Raman intensities by evaluating the variation of the polarizability tensors for finite displacements of the atoms. Calculated intensities agree well with experimental data, showing an average error of 13% for relative intensities. Using our first-principles results as reference, we critically examine simple models for the Raman activity. We first consider a bond polarizability model, for which the parameters are derived from our first-principles results for ␣-quartz. This model reproduces the first-principles intensities with an average error of 15%. In the attempt of reducing this error, we then introduce a model in which the symmetry of the first neighbor shell is accounted for in the most general way. For ␣-quartz, this model extends the bond polarizability model, which is recovered as a special case. The model, which fully accounts for the local symmetry, describes the first-principles results within an average error of 12%, marginally improving upon the bond polarizability model ͑15%͒. However, when these models with parameters derived for ␣-quartz are applied to a cristobalite polymorph, only the bond polarizability model shows good transferability properties. These results support the use of the bond polarizability model as a simple scheme for calculating Raman intensities in tetrahedrally bonded SiO 2 systems.

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