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  • 1
    Electronic Resource
    Electronic Resource
    Inoculation of rice with nitrogen-fixing bacteria —problems and perspectives (1987)
    Springer
    Biology and fertility of soils 4 (1987), S. 21-26 
    Details
    ISSN: 1432-0789
    Keywords: Bacterial inoculation ; Rice yield ; Associative nitrogen fixation ; Azotobacter spp. ; Azospirillum spp. ; Pseudomonas spp. ; Rhizosphere
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The present status and merits of inoculating rice with N2-fixing bacteria are discussed in the light of recent advances. Bacterial inoculation improves plant growth and rice yield but not uniformly. The yield response to inoculation is more pronounced in the presence of moderate levels of fertilizer N. Evidence for the establishment and activity of the inoculated bacteria is limited, and the poor survival of the inoculum under field conditions further complicates the effects of inoculation. There is no clear evidence that improved growth and mineral content following inoculation are due to increased N2 fixation. Beneficial effects of the inoculum on rice, such as plant growth promotion, N2 fixation and antagonism effects against pathogens need to be further investigated under laboratory and field conditions. Improved management practices, such as organic amendments, suitable water and soil management, selection of efficient microbial strains, selection of effective breeding lines with high associative nitrogen fixation, and better management of agrochemicals are some of the measures suggested for deriving benefits from bacterial associations with rice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00280346
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  • 2
    Electronic Resource
    Electronic Resource
    Electronic structure of chromium oxides, CrOn− and CrOn (n=1–5) from photoelectron spectroscopy and density functional theory calculations (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 7935-7944 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The electronic structure of CrOn− and CrOn (n=1–5) was investigated using anion photoelectron spectroscopy and density functional theory. Photoelectron spectra of CrOn− were obtained at several photon energies and yielded electron affinities, vibrational and electronic structure information about the neutral CrOn species. Density functional theory calculations were carried out for both the neutrals and anions and were used to interpret the experimental spectra. Several low-lying electronic states of CrO were observed and assigned from photodetachment of the CrO− ground state (6∑+) and an excited state (4∏), which is only 0.1 eV higher. The main spectral features of CrO2− were interpreted based on a C2v CrO2− (4B1). A very weak Cr(O2)− isomer was also observed with lower electron binding energies. Relatively simple and vibrationally resolved spectra were observed for CrO3−, which was determined to be D3h. The CrO3 neutral was calculated to be C3v with the Cr atom slightly out of the plane of the three O atoms. The spectrum of CrO4− revealed a very high electron binding energy. Several isomers of CrO4− were predicted and the ground state has a distorted tetrahedral structure (C2) without any O–O bonding. Only one stable structure was predicted for CrO5− with a superoxo O2 bonded to a C3v CrO3. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1405438
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  • 3
    Electronic Resource
    Electronic Resource
    Electronic structure and chemical bonding of 3d-metal dimers ScX, X=Sc–Zn (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 10738-10748 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The electronic and geometrical structures of the ground and excited states of the homonuclear Sc2, mixed ScTi, ScV, ScCr, ScMn, ScFe, ScCo, ScNi, ScCu, and ScZn 3d-metal dimers and their anions have been calculated using the density functional theory with generalized gradient approximation for the exchange-correlation potential. The ground states of the neutral dimers are found to be 5Σu− (Sc2), 6Σ+ (ScTi), 7Σ+ (ScV), 4Σ+ (ScCr), 3Σ+ (ScMn), 2Δ(ScFe), 1Σ+ (ScCo), 2Σ+ (ScNi), 3Δ(ScCu), and 4Σ+ (ScZn). A natural bond analysis reveals an antiferrimagnetic spin coupling in the ground states of ScCr, ScMn, and ScFe. This is due to the electron transfer from Sc to the opposite atom and specific bond formations. While each dimer has a unique chemical bonding pattern, most curious is the localization of two 4s electrons at both atomic sites in the ground 5Σu− state of Sc2, which leads to formation of two lone pairs and the bonding scheme: (3d+3d)α3(4s+4s)β1. No appreciable sd hybridization is found for the ground states of the ScX dimers except for ScNi. Even though the electron affinities of the ScX dimers are relatively low and do not exceed 1 eV, each ScX− (except ScCo−) possesses at least two states stable towards detachment of an extra electron. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1373693
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  • 4
    Electronic Resource
    Electronic Resource
    Geometry, electronic structure, and energetics of copper-doped aluminum clusters (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 114 (2001), S. 9792-9796 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Using density functional theory and generalized gradient approximation for exchange-correlation potential, we have calculated the equilibrium geometries and energetics of neutral and negatively charged AlnCu (n=11,12,13,14) clusters. Unlike the alkali atom-doped aluminum clusters in the same size range, the copper atom resides inside the aluminum cluster cage. Furthermore, the 3d and 4s energy levels of Cu hybridize with the valence electrons of Al causing a redistribution of the molecular orbital energy levels of the Aln clusters. However, this redistribution does not affect the magic numbers of AlnCu clusters that could be derived by assuming that Cu donates one electron to the valence levels of Aln clusters. This behavior, brought about by the smaller size and large ionization potential of the copper atom, contributes to the anomalous properties of AlnCu− anions: Unlike AlnX− (X=alkali atom), the mass ion intensities of AlnCu− are similar to those of Aln−. The calculated adiabatic electron affinities are also in very good agreement with experiment. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1367381
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  • 5
    Electronic Resource
    Electronic Resource
    Experimental and theoretical study of the photoelectron spectra of MnOx−(x=1–3) clusters (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 1473-1483 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report a combined experimental and theoretical investigation of MnOx− and MnOx(x=1–3) clusters. Theoretically, geometrical configurations of various isomers of the clusters were optimized and vertical detachment energies for the anions were evaluated. The ground state of MnO− was predicted to be 5Σ+, followed by an excited state (7Σ+) 0.14 eV higher in energy. The ground state of MnO2− is 5B2, with a 3B1 isomer 0.15 eV higher. MnO3− is predicted to be a singlet D3h cluster. Vibrationally resolved photoelectron spectra of MnOx− were measured at several photon energies and under various experimental conditions, and were interpreted based on the theoretical results. The electron affinities of MnO, MnO2, and MnO3 were determined to be 1.375 (0.010), 2.06 (0.03), and 3.335 (0.010), respectively. Five excited states of MnO were observed and assigned using the theoretical results. The 7Σ+ excited state of MnO− was found to be significantly populated and was distinguished from the ground state of the anion by temperature dependent studies. We observed two isomers for MnO2− and the detachment features from both isomers were assigned. Only one vibrationally resolved band was observed for MnO3−, which corresponds to transitions from the ground state of MnO3− to that of MnO3. The combined experimental and theoretical studies allow us to elucidate the complicated electronic and geometric structures of the various manganese oxide clusters and their anions. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481964
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  • 6
    Electronic Resource
    Electronic Resource
    Alkalization of aluminum clusters (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 113 (2000), S. 1508-1513 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Equilibrium geometries, binding energies, ionization potentials, and electron affinities of neutral and charged Aln clusters (n≤8) decorated with alkali atoms such as Li and K have been calculated using molecular orbital theory based on density functional formalism and generalized gradient approximation. While the electron affinities and the ionization potentials depend on size, no clear signatures of shell closings are found in this size range. Similar studies on Al5Xm (X=Li, K, 1≤m≤4) also fail to provide any indication consistent with shell closings. On the other hand, the ionization potentials and electron affinities of aluminum clusters decrease with the addition of alkali atoms. The results are in good agreement with available experimental data. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.481937
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  • 7
    Electronic Resource
    Electronic Resource
    Caging of Ni clusters by benzene molecules and its effect on the magnetism of Ni clusters (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 1343-1349 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Global optimization of the geometry of small Ni clusters interacting with benzene molecules yields equilibrium structures where the Ni atoms find themselves caged between the benzene molecules. This leads to quenching of the Ni magnetic moment in most of the complexes even though the structure of the caged Ni clusters remain relatively unchanged from their otherwise free gas phase geometry. The accuracy of these predictions, based on density functional theory with generalized gradient approximation for exchange and correlation, is established by the good agreement achieved between the calculated and available experimental dissociation energies and ionization potentials. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1429245
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  • 8
    Electronic Resource
    Electronic Resource
    Energetics and electronic structure of carbon doped aluminum clusters (2001)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 115 (2001), S. 778-783 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The energetics and the electronic structure of AlnC clusters (n=3, 4, 5; 11, 12, 13) have been studied by a global optimization of their geometry without any symmetry constraint. The total energies of these clusters both in neutral and charged states are calculated using an all-electron basis and the generalized gradient approximation to the density functional theory. While Al4C and Al12C clusters share some characteristic features of closed shell structures, namely enhanced stability and low electron affinity compared to their neighboring sizes, their ionization potentials exhibit different behavior. These decrease steadily from Al3C to Al5C while that of Al12C is higher than its neighbors. Carbon is found to form planar structures in small AlnC clusters (n=3, 4, 5) irrespective of their charge state although neutral Al4C possesses a nearly degenerate tetrahedral isomer lying slightly higher in energy from the planar configuration. The results agree well with experimental and previous theoretical data. In larger AlnC (n=11, 12, 13) clusters, carbon occupies an interior site. In Al12C, carbon occupies the center of an icosahedron while it is off-centered in Al11C and Al13C. As an electron is attached, the near degeneracies of the neutral Al4C is lifted whereas nondegenerate isomers of neutral Al12C yield nearly degenerate anions. Both these features produce complicated photoelectron spectra making identification of their adiabatic electron affinity a difficult problem. With the exception of neutral Al12C, the bonding of carbon to aluminum atoms is governed primarily by covalent interaction. The above calculations were also performed with a simplified basis by freezing the atomic cores of aluminum. In most cases, this simple basis yields results in good agreement with all electron calculations. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1379973
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  • 9
    Electronic Resource
    Electronic Resource
    Statistical-mechanical perturbation theory for liquid metals
    Amsterdam : Elsevier
    Physics Letters A 41 (1972), S. 200-202 
    Details
    ISSN: 0375-9601
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0375-9601(72)90258-7
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  • 10
    Electronic Resource
    Electronic Resource
    Limitation on the success of the jellium model for metal clusters
    Amsterdam : Elsevier
    Chemical Physics Letters 183 (1991), S. 333-336 
    Details
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0009-2614(91)90387-O
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