zeljko crljen - Academia.edu (original) (raw)
Papers by zeljko crljen
arXiv (Cornell University), Oct 15, 2014
We showed how a structural modification of graphene, which gives a carbon allotrope graphyne, can... more We showed how a structural modification of graphene, which gives a carbon allotrope graphyne, can induce an energy gap at the K point of the Brillouin zone. Upon adsorption on metallic surfaces, the same mechanism is responsible for the further modification of the energy gap which occurs via the charge transfer mechanism. We performed the calculation based on the density functional theory with the novel non-local vdW-DF correlation of the adsorption of graphyne on Cu(111), Ni(111) and Co(0001) surfaces and showed the dependence of the gap change on the charge transfer in the system. The binding of graphyne appears to be stronger than of graphene on the same surfaces.
World Academy of Science, Engineering and Technology, International Journal of Physical and Mathematical Sciences, 2017
Springer Series in Solid-State Sciences, 1990
Surface Science Letters, 1984
ABSTRACT
Springer Series in Solid-State Sciences, 1993
In order to calculate the optical conductivity of HTSC, we first consider the optical response of... more In order to calculate the optical conductivity of HTSC, we first consider the optical response of related small clusters. In this way, the photoabsorption cross section of a CuO2 molecule is calculated in the TDLDA via one-centre expansion around the Cu site. The resulting absorption shows strong oscillations due to molecular structure.
Physical Review B, 1984
The reduction of the specular-beam intensity in the scattering of thermalized He atoms from dense... more The reduction of the specular-beam intensity in the scattering of thermalized He atoms from densely packed surfaces of metals is irivestigated in terms of nonadiabatic multiple excitation of low-energy surface electronic density fluctuations. Their effect on the atom-scattering spectra is studied within the time-dependent approach developed by Doniach and Muller-Hartmann, Ramakrishnan, and Toulouse to treat localized perturbations in metals. This mechanism may explain the peculiar coexistence of the unitarity defect with the absence of diffractive peaks as reported recently for the system He/Cu(100).
Physical Review B, 2003
The growth and structure of ultrathin silver films ͑1-5 monolayers thick͒ deposited on a reconstr... more The growth and structure of ultrathin silver films ͑1-5 monolayers thick͒ deposited on a reconstructed V(100)-(5ϫ1) surface have been studied by means of scanning tunneling microscopy ͑STM͒, Auger electron spectroscopy ͑AES͒, and angle-resolved photoemission spectroscopy ͑ARPES͒. To model the structure of the system we have also performed density functional ͑DFT͒ calculations. It has been established that due to the annealing of deposited silver uniform films are formed and that the vanadium reconstruction is completely removed. As found from STM measurements and supported by ab initio calculations in the in-plane direction silver follows the structure of the V(100)-(1ϫ1) lattice and is tetragonally distorted in the direction perpendicular to the surface. In addition, ab initio results predicted the adsorption energies of individual silver layers and the work function of Ag/V͑100͒, both in accordance with experiments.
Surface Science, 1983
ABSTRACT
Physical Review B, 2005
We theoretically study the electronic transport in the monolayer of dithiolated phenylene vinylen... more We theoretically study the electronic transport in the monolayer of dithiolated phenylene vinylene oligomeres coupled to the (111) surfaces of gold electrodes. We use non-equilibrium Green functions (NEGF) and density functional theory(DFT) implemented in the TranSIESTA package to obtain a full ab initio self-consistent description of the transport current through the molecular nanostructure with different electrochemical bias potentials. The calculated current-voltage characteristics (IVC) of the systems for the same contact geometry have shown a systematic decrease of the conductivity with the increased length of the molecules. We analyze the results in terms of transmission eigenchannels and find that besides the delocalization of molecular orbitals the distance between gold electrodes also determines the transport properties.
Physical Review B, 2006
We study the variation of electron transmission through Au-S-benzene-S-Au junctions and related s... more We study the variation of electron transmission through Au-S-benzene-S-Au junctions and related systems as a function of the structure of the Au:S contacts. For junctions with semi-infinite flat Au(111) electrodes, the highly coordinated in-hollow and bridge positions are connected with broad transmission peaks around the Fermi level, due to a broad range of transmission angles from transverse motion, resulting in high conductivity and weak dependence on geometrical variations. In contrast, for (unstable) S-adsorption on top of an Au atom, or in the hollow of a 3-Au-atom island, the transmission peaks narrow up due to suppression of large transmission angles. Such more one-dimensional situations may describe more common types of contacts and junctions, resulting in large variations in conductivity and sensitivity to bonding sites, tilting and gating. In particular, if S is adsorbed in an Au vacancy, sharp spectral features appear near the Fermi level due to essential changes of the level structure and hybridization in the contacts, admitting order-of-magnitude variations of the conductivity. Possibly such a system, can it be fabricated, will show extremely strong non-linear effects and might work as uni-or bi-directional voltage-controlled 2-terminal switches and non-linear mixing elements. Finally, density-functional-theory (DFT) based transport calculations seem relevant, being capable of describing a wide range of transmission peak structures and conductivities. Prediction and interpretation of experimental results probably require more precise modeling of realistic experimental situations.
Physica C: Superconductivity and its Applications, 1989
ABSTRACT
Le Journal de Physique IV, 2000
The identification of strongly correlated double electron local sites in semiconductors usually r... more The identification of strongly correlated double electron local sites in semiconductors usually requires a nonequilibrium situation in order to observe a single occupied state of a local site. We present a way of a direct observation of negative-U centers by means of a single photon optical transition from band states into local states provided controlled occupancy of local levels via doping the semiconductor or via change of the gate voltage. The photoabsorption spectrum shows single and double electron transitions as the consequence of the hybridization of local states and band electron states. The value of the correlation energy in localized states determine positions and intensities of peaks while the occupancy of local levels reflects itself in the line shape. A qualitative comparison with available data on installed atoms as possible double electron centers in semiconductors is made.
Physical Review Letters, 2007
We report a full self-consistent ab initio calculation of the current-voltage curve and the condu... more We report a full self-consistent ab initio calculation of the current-voltage curve and the conductance of thiolate capped polyynes in contact with gold electrodes. We find the conductance of polyynes an order of magnitude larger compared with other conjugated oligomers. The reason lies in the position of the Fermi level deep in the HOMO related resonance. With the conductance weakly dependent on the applied bias and almost independent of the length of the molecular chain, polyynes appear as nearly perfect molecular wires.
Springer Series in Solid-State Sciences, 1993
The linear and nonlinear optical absorption as well as normal state tunneling is investigated wit... more The linear and nonlinear optical absorption as well as normal state tunneling is investigated within the local-pair model for high Tc materials. Doping dependence of absorption peaks and linear voltage dependence of tunneling conductance is obtained in a qualitative agreement with experiments.
Phys Rev a, 1994
Page 1. PHYSICAL REVIEW A VOLUME 50, NUMBER 4 OCTOBER 1994 Collective response and molecular effe... more Page 1. PHYSICAL REVIEW A VOLUME 50, NUMBER 4 OCTOBER 1994 Collective response and molecular effects in cluster photoionization: A one-center time-dependent calculation for Saon Zeljko Crljen, Jarek Luberek, and ...
Eur Phys J B, 1993
ABSTRACT
Journal of Superconductivity - J SUPERCOND, 2001
By exact diagonalization of a small cluster, we show that an interplay of electron–phonon and ons... more By exact diagonalization of a small cluster, we show that an interplay of electron–phonon and onsite electron–electron interactions results in “intersite” or “onsite” two-electron (bipolaronic) solutions of the Holstein–Hubbard model, depending on the strengths of the interactions. On this basis, we argue that the decrease in the superconducting transition temperature of Bi-2212 compounds, following the enhancement of the electron–phonon interaction recently reported by Devereaux et al. [10] might be a consequence of the above mechanism, which leads to a transition from itinerant (intersite) to bound immobile (onsite) bipolarons, thus effectively reducing the number of superconducting carriers.
arXiv (Cornell University), Oct 15, 2014
We showed how a structural modification of graphene, which gives a carbon allotrope graphyne, can... more We showed how a structural modification of graphene, which gives a carbon allotrope graphyne, can induce an energy gap at the K point of the Brillouin zone. Upon adsorption on metallic surfaces, the same mechanism is responsible for the further modification of the energy gap which occurs via the charge transfer mechanism. We performed the calculation based on the density functional theory with the novel non-local vdW-DF correlation of the adsorption of graphyne on Cu(111), Ni(111) and Co(0001) surfaces and showed the dependence of the gap change on the charge transfer in the system. The binding of graphyne appears to be stronger than of graphene on the same surfaces.
World Academy of Science, Engineering and Technology, International Journal of Physical and Mathematical Sciences, 2017
Springer Series in Solid-State Sciences, 1990
Surface Science Letters, 1984
ABSTRACT
Springer Series in Solid-State Sciences, 1993
In order to calculate the optical conductivity of HTSC, we first consider the optical response of... more In order to calculate the optical conductivity of HTSC, we first consider the optical response of related small clusters. In this way, the photoabsorption cross section of a CuO2 molecule is calculated in the TDLDA via one-centre expansion around the Cu site. The resulting absorption shows strong oscillations due to molecular structure.
Physical Review B, 1984
The reduction of the specular-beam intensity in the scattering of thermalized He atoms from dense... more The reduction of the specular-beam intensity in the scattering of thermalized He atoms from densely packed surfaces of metals is irivestigated in terms of nonadiabatic multiple excitation of low-energy surface electronic density fluctuations. Their effect on the atom-scattering spectra is studied within the time-dependent approach developed by Doniach and Muller-Hartmann, Ramakrishnan, and Toulouse to treat localized perturbations in metals. This mechanism may explain the peculiar coexistence of the unitarity defect with the absence of diffractive peaks as reported recently for the system He/Cu(100).
Physical Review B, 2003
The growth and structure of ultrathin silver films ͑1-5 monolayers thick͒ deposited on a reconstr... more The growth and structure of ultrathin silver films ͑1-5 monolayers thick͒ deposited on a reconstructed V(100)-(5ϫ1) surface have been studied by means of scanning tunneling microscopy ͑STM͒, Auger electron spectroscopy ͑AES͒, and angle-resolved photoemission spectroscopy ͑ARPES͒. To model the structure of the system we have also performed density functional ͑DFT͒ calculations. It has been established that due to the annealing of deposited silver uniform films are formed and that the vanadium reconstruction is completely removed. As found from STM measurements and supported by ab initio calculations in the in-plane direction silver follows the structure of the V(100)-(1ϫ1) lattice and is tetragonally distorted in the direction perpendicular to the surface. In addition, ab initio results predicted the adsorption energies of individual silver layers and the work function of Ag/V͑100͒, both in accordance with experiments.
Surface Science, 1983
ABSTRACT
Physical Review B, 2005
We theoretically study the electronic transport in the monolayer of dithiolated phenylene vinylen... more We theoretically study the electronic transport in the monolayer of dithiolated phenylene vinylene oligomeres coupled to the (111) surfaces of gold electrodes. We use non-equilibrium Green functions (NEGF) and density functional theory(DFT) implemented in the TranSIESTA package to obtain a full ab initio self-consistent description of the transport current through the molecular nanostructure with different electrochemical bias potentials. The calculated current-voltage characteristics (IVC) of the systems for the same contact geometry have shown a systematic decrease of the conductivity with the increased length of the molecules. We analyze the results in terms of transmission eigenchannels and find that besides the delocalization of molecular orbitals the distance between gold electrodes also determines the transport properties.
Physical Review B, 2006
We study the variation of electron transmission through Au-S-benzene-S-Au junctions and related s... more We study the variation of electron transmission through Au-S-benzene-S-Au junctions and related systems as a function of the structure of the Au:S contacts. For junctions with semi-infinite flat Au(111) electrodes, the highly coordinated in-hollow and bridge positions are connected with broad transmission peaks around the Fermi level, due to a broad range of transmission angles from transverse motion, resulting in high conductivity and weak dependence on geometrical variations. In contrast, for (unstable) S-adsorption on top of an Au atom, or in the hollow of a 3-Au-atom island, the transmission peaks narrow up due to suppression of large transmission angles. Such more one-dimensional situations may describe more common types of contacts and junctions, resulting in large variations in conductivity and sensitivity to bonding sites, tilting and gating. In particular, if S is adsorbed in an Au vacancy, sharp spectral features appear near the Fermi level due to essential changes of the level structure and hybridization in the contacts, admitting order-of-magnitude variations of the conductivity. Possibly such a system, can it be fabricated, will show extremely strong non-linear effects and might work as uni-or bi-directional voltage-controlled 2-terminal switches and non-linear mixing elements. Finally, density-functional-theory (DFT) based transport calculations seem relevant, being capable of describing a wide range of transmission peak structures and conductivities. Prediction and interpretation of experimental results probably require more precise modeling of realistic experimental situations.
Physica C: Superconductivity and its Applications, 1989
ABSTRACT
Le Journal de Physique IV, 2000
The identification of strongly correlated double electron local sites in semiconductors usually r... more The identification of strongly correlated double electron local sites in semiconductors usually requires a nonequilibrium situation in order to observe a single occupied state of a local site. We present a way of a direct observation of negative-U centers by means of a single photon optical transition from band states into local states provided controlled occupancy of local levels via doping the semiconductor or via change of the gate voltage. The photoabsorption spectrum shows single and double electron transitions as the consequence of the hybridization of local states and band electron states. The value of the correlation energy in localized states determine positions and intensities of peaks while the occupancy of local levels reflects itself in the line shape. A qualitative comparison with available data on installed atoms as possible double electron centers in semiconductors is made.
Physical Review Letters, 2007
We report a full self-consistent ab initio calculation of the current-voltage curve and the condu... more We report a full self-consistent ab initio calculation of the current-voltage curve and the conductance of thiolate capped polyynes in contact with gold electrodes. We find the conductance of polyynes an order of magnitude larger compared with other conjugated oligomers. The reason lies in the position of the Fermi level deep in the HOMO related resonance. With the conductance weakly dependent on the applied bias and almost independent of the length of the molecular chain, polyynes appear as nearly perfect molecular wires.
Springer Series in Solid-State Sciences, 1993
The linear and nonlinear optical absorption as well as normal state tunneling is investigated wit... more The linear and nonlinear optical absorption as well as normal state tunneling is investigated within the local-pair model for high Tc materials. Doping dependence of absorption peaks and linear voltage dependence of tunneling conductance is obtained in a qualitative agreement with experiments.
Phys Rev a, 1994
Page 1. PHYSICAL REVIEW A VOLUME 50, NUMBER 4 OCTOBER 1994 Collective response and molecular effe... more Page 1. PHYSICAL REVIEW A VOLUME 50, NUMBER 4 OCTOBER 1994 Collective response and molecular effects in cluster photoionization: A one-center time-dependent calculation for Saon Zeljko Crljen, Jarek Luberek, and ...
Eur Phys J B, 1993
ABSTRACT
Journal of Superconductivity - J SUPERCOND, 2001
By exact diagonalization of a small cluster, we show that an interplay of electron–phonon and ons... more By exact diagonalization of a small cluster, we show that an interplay of electron–phonon and onsite electron–electron interactions results in “intersite” or “onsite” two-electron (bipolaronic) solutions of the Holstein–Hubbard model, depending on the strengths of the interactions. On this basis, we argue that the decrease in the superconducting transition temperature of Bi-2212 compounds, following the enhancement of the electron–phonon interaction recently reported by Devereaux et al. [10] might be a consequence of the above mechanism, which leads to a transition from itinerant (intersite) to bound immobile (onsite) bipolarons, thus effectively reducing the number of superconducting carriers.