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From the South Side of Chicago to Berkeley, California with Stops in Between. J Phys Chem A 2022; 126:4123-4131. [PMID: 35708518 DOI: 10.1021/acs.jpca.2c03533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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From the South Side of Chicago to Berkeley, California with Stops in Between. J Phys Chem B 2022; 126:4745-4753. [PMID: 35708519 DOI: 10.1021/acs.jpcb.2c03534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Anti-platelet factor 4 immunoglobulin G levels in vaccine-induced immune thrombocytopenia and thrombosis: Persistent positivity through 7 months. Res Pract Thromb Haemost 2022; 6:e12707. [PMID: 35515079 PMCID: PMC9066380 DOI: 10.1002/rth2.12707] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 03/10/2022] [Accepted: 03/18/2022] [Indexed: 12/31/2022] Open
Abstract
Background Anti-platelet factor 4 (PF4) antibodies that activate platelets via FcγRIIA drive the pathophysiology of vaccine-induced immune thrombocytopenia and thrombosis (VITT). Evolution of these antibodies and their ability to activate platelets after initial treatment remains unknown. Objectives To assess how clinical and platelet parameters, anti-PF4 antibody levels, and patient serum reactivity changes during follow-up after VITT presentation. Methods We describe cases of seven discharged VITT patients that were followed from diagnosis up to 280 days (range 199-280) after vaccination. We measured anti-PF4 antibodies and PF4 levels in patient serum during follow-up and tested the ability of patient serum to activate healthy donor platelets and patient platelets over time. Results Anti-PF4 immunoglobulin G antibody levels are very high at diagnosis (0.9-2.6 OD) and remain relatively high (>1.0 OD) in all patients, except one treated with rituximab, at 7 months post vaccination. All patients were on direct oral anticoagulants throughout follow-up and no patients had recurrent thrombosis. Patients' platelets during follow-up have normal FcγRIIA levels and responsiveness to platelet agonists. Patient diagnostic serum strongly activated control platelets, either alone or with PF4. Most follow-up serum alone was weaker at stimulating donor and patient platelets. However, follow-up serum beyond 150 days still strongly activated platelets with PF4 addition in three patients. Patient serum PF4 levels were lower than controls at diagnosis but returned within normal range by day 50. Conclusions Explanations for reduced platelet activation during follow-up, despite similar total anti-PF4 antibody levels, remains unclear. Clinical implications of persistent anti-PF4 antibodies in VITT require further study.
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Quantum Monte Carlo Study of the Reactions of CH with Acrolein: Major and Minor Channels. J Phys Chem A 2016; 120:3602-12. [DOI: 10.1021/acs.jpca.5b11527] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
To assist understanding of combustion processes, we have investigated reactions of methylidyne (CH) with acrolein (CH2CHCHO) using the quantum Monte Carlo (QMC) and other computational methods. We present a theoretical study of the major reactions reported in a recent experiment on the subject system. Both DFT and MP2 computations are carried out, and the former approach is used to form the independent-particle part of the QMC trial wave function used in the diffusion Monte Carlo (DMC) variant of the QMC method. In agreement with experiment, we find that the dominant product channel leads to formation of C4H4O systems + H with leading products of furan + H and 1,3-butadienal + H. Equilibrium geometries, atomization energies, reaction barriers, transition states, and heats of reaction are computed using the DFT, MP2, and DMC approaches and compared to experiment. We find that DMC results are in close agreement with experiment. The kinetics of the subject reactions are determined by solving master equations with the MultiWell software suite.
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Interval prediction of molecular properties in parametrized quantum chemistry. PHYSICAL REVIEW LETTERS 2014; 112:253003. [PMID: 25014809 DOI: 10.1103/physrevlett.112.253003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Indexed: 06/03/2023]
Abstract
The accurate evaluation of molecular properties lies at the core of predictive physical models. Most reliable quantum-chemical calculations are limited to smaller molecular systems while purely empirical approaches are limited in accuracy and reliability. A promising approach is to employ a quantum-mechanical formalism with simplifications and to compensate for the latter with parametrization. We propose a strategy of directly predicting the uncertainty interval for a property of interest, based on training-data uncertainties, which sidesteps the need for an optimum set of parameters.
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Abstract
Energetics and kinetics of the oxidation of possible soot surface sites by hydroxyl radicals were investigated theoretically. Energetics were calculated by employing density functional theory. Three candidate reactions were selected as suitable prototypes of soot oxidation by OH. The first two, OH + benzene and OH + benzene-phenol complex, did not produce pathways that lead to substantial CO expulsion. The third reaction, OH attack on the phenanthrene radical, had multiple pathways leading to CO elimination. The kinetics of the latter reaction system were determined by solving the master equations with the MultiWell suite of codes. The barrierless reaction rates of this system were computed using the VariFlex program. The computations were carried out over the ranges 1500-2500 K and 0.01-10 atm. At higher temperatures, above 2000 K, the oxidation of phenanthrene radicals by OH followed a chemically activated path. At temperatures lower than 2000 K, chemical activation was not sufficient to drive the reaction to products; reaction progress was impeded by intermediate adducts rapidly de-energizing before reaching products. In such cases, the reaction system was modeled by treating the accumulating adducts as distinct chemical species and computing their kinetics via thermal decomposition. The overall rate coefficient of phenanthrene radical oxidation by OH forming CO was found to be insensitive to pressure and temperature and is approximately 1 × 10(14) cm(3) mol(-1) s(-1). The oxidation of phenanthrene radicals by OH is shown to be controlled by two main processes: H atom migration/elimination and oxyradical decomposition. H atom migration and elimination made possible relatively rapid rearrangement of the aromatic edge to form oxyradicals with favorable decomposition rates. The reaction then continues down the fastest oxyradical pathways, eliminating CO.
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Quantum Monte Carlo for the x-ray absorption spectrum of pyrrole at the nitrogen K-edge. J Chem Phys 2012; 136:144301. [DOI: 10.1063/1.3700803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Edge versus interior in the chemical bonding and magnetism of zigzag edged triangular graphene molecules. J Chem Phys 2010; 133:044708. [DOI: 10.1063/1.3457673] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Abstract
Patterns of localized and delocalized chemical bonding obtained using the recently proposed adaptive natural density partitioning (AdNDP) provide a qualitative description of electronic structure but miss any quantitative information. Descriptors, such as the electron localization function (ELF), provide quantitative characteristics of bonding and can enhance the usefulness of qualitative patterns. In the present study, we used ELF and a related construct, charge-density-weighted ELF (ELF rho), to characterize localized and delocalized bonding in a variety of systems. It is demonstrated that ELF rho yields a more detailed description than ELF when used to analyze bonding in aromatic, conflicting aromatic, and antiaromatic systems. Both canonical molecular orbitals (CMOs) and localized multicenter two-electron (nc-2e) bonds obtained in the latter case by AdNDP localization are used to calculate ELF rho.
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Onset of diradical character in small nanosized graphene patches. Phys Chem Chem Phys 2010; 12:9839-44. [DOI: 10.1039/c003708g] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Intramolecular competition in the photodissociation of C3D3 radicals at 248 and 193 nm. Phys Chem Chem Phys 2010; 12:10714-22. [DOI: 10.1039/c0cp00380h] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Management of patients taking antiplatelet or anticoagulant medication requiring invasive breast procedures: United Kingdom survey of radiologists' and surgeons' current practice. Clin Radiol 2008; 63:305-11. [PMID: 18275871 DOI: 10.1016/j.crad.2007.09.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2007] [Accepted: 09/14/2007] [Indexed: 11/28/2022]
Abstract
AIM To determine the current practice in the UK National Health Service Breast Screening Programme for invasive diagnostic procedures and surgery in patients taking anticoagulant and antiplatelet medication. MATERIALS AND METHODS Lead radiologists and surgeons at each breast screening service were surveyed to determine current practice. One hundred and five respondents provided information regarding their services, protocols, and willingness to proceed with combinations of procedures and anti-haemostatic medications. RESULTS Between units there was wide variation in practice. Within 21 services providing more than one response, 10 (48%) disagreed on whether protocols existed. Decisions to perform biopsies were unrelated to professional group. The taking of a drug history was variable. Surgeons reported more adverse effects than radiologists [21 (48%) versus 12 (26%)], but no difference in self-assessment of knowledge. CONCLUSION Both radiologists and surgeons have expressed uncertainty about their understanding of anticoagulant and antiplatelet treatment. This is reflected in a wide range of practice. Guidance regarding the management of these patients is suggested.
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Abstract
Electrophilic amination is an appealing synthetic strategy to construct carbon-nitrogen bonds. The authors explore the use of the quantum Monte Carlo method and a proposed variant of the electron pair localization function--the electron pair localization function density--as a measure of the nucleophilicity of nitrogen lone pairs as a possible screening procedure for electrophilic reagents.
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Quantum Monte Carlo study of first-row atoms using transcorrelated variational Monte Carlo trial functions. J Chem Phys 2007; 126:164109. [PMID: 17477591 DOI: 10.1063/1.2715581] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The effect of using the transcorrelated variational Monte Carlo (TC-VMC) approach to construct a trial function for fixed node diffusion Monte Carlo (DMC) energy calculations has been investigated for the first-row atoms, Li to Ne. The computed energies are compared with fixed node DMC energies obtained using trial functions constructed from Hartree-Fock and density functional levels of theory. Despite major VMC energy improvement with TC-VMC trial functions, no improvement in DMC energy was observed using these trial functions for the first-row atoms studied. The implications of these results on the nodes of the trial wave functions are discussed.
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The R2464C missense mutation in the von Willebrand factor gene causes a novel abnormality of multimer electrophoretic mobility and falls into the subgroup of type 2 von Willebrand disease 'unclassified'. Thromb Haemost 2007; 97:159-60. [PMID: 17200787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
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Inherited and de novo von Willebrand disease 'Vicenza' in UK families with the R1205H mutation: diagnostic pitfalls and new insights. Br J Haematol 2006; 135:91-6. [PMID: 16925796 DOI: 10.1111/j.1365-2141.2006.06251.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
von Willebrand disease (VWD) caused by the R1205H mutation has distinct and reproducible clinical and laboratory features. This report describes the phenotypic and molecular investigation of seven kindreds with VWD Vicenza R1205H. All affected individuals have historically been diagnosed with moderate to severe type 1 VWD. Amongst all families with highly penetrant type 1 VWD investigated at our centre, heterozygosity for the R1205H mutation was found to be the most common underlying molecular defect. A severe laboratory phenotype associated with a bleeding history that was milder than expected was commonly observed, consistent with previous published case reports; however, abnormal ultralarge high molecular weight multimers were not detected in resting plasma samples. We also provide evidence that the R1205H mutation may arise de novo--evidence that a common genetic origin for this mutation is unlikely.
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Abstract
The Zori 1.0 package for electronic structure computations is described. Zori performs variational and diffusion Monte Carlo computations as well as correlated wave function optimization. This article presents an overview of the implemented methods and code capabilities.
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A sparse algorithm for the evaluation of the local energy in quantum Monte Carlo. J Comput Chem 2005; 26:708-15. [PMID: 15761862 DOI: 10.1002/jcc.20205] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A new algorithm is presented for the sparse representation and evaluation of Slater determinants in the quantum Monte Carlo (QMC) method. The approach, combined with the use of localized orbitals in a Slater-type orbital basis set, significantly extends the size molecule that can be treated with the QMC method. Application of the algorithm to systems containing up to 390 electrons confirms that the cost of evaluating the Slater determinant scales linearly with system size.
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Quantum Monte Carlo: Theory and Application to Molecular Systems. ADVANCES IN QUANTUM CHEMISTRY 2005. [DOI: 10.1016/s0065-3276(05)49004-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
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Abstract
A theoretical study is reported of the Cl+CH3OH-->CH2OH+HCl reaction based on the diffusion Monte Carlo (DMC) variant of the quantum Monte Carlo method. Using a DMC trial function constructed as a product of Hartree-Fock and correlation functions, we have computed the barrier height, heat of reaction, atomization energies, and heats of formation of reagents and products. The DMC heat of reaction, atomization energies, and heats of formation are found to agree with experiment to within the error bounds of computation and experiment. Møller-Plesset second order perturbation theory (MP2) and density functional theory, the latter in the B3LYP generalized gradient approximation, are found to overestimate the experimental heat of reaction. Intrinsic reaction coordinate calculations at the MP2 level of theory demonstrate that the reaction is predominantly direct, i.e., proceeds without formation of intermediates, which is consistent with a recent molecular beam experiment. The reaction barrier as determined from MP2 calculations is found to be 2.24 kcal/mol and by DMC it is computed to be 2.39(49) kcal/mol.
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Abstract
Accurate calculations of allowed and nonallowed transitions in porphyrin are reported. Using the quantum Monte Carlo method in the diffusion Monte Carlo variant, the vertical transition between the ground state singlet and the second excited state singlet as well as the adiabatic transition between the ground state and the lowest triplet state have been computed for this 162-electron system. The present theoretical results are compared to experiment and to results of other theoretical methods. The diffusion Monte Carlo energy differences are found to be in excellent agreement with experiment.
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Comparative Study on the Interaction of Scandium and Copper Atoms with Small Silicon Clusters. J Phys Chem A 2002. [DOI: 10.1021/jp021668y] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Soft pseudopotentials for efficient quantum Monte Carlo calculations: From Be to Ne and Al to Ar. J Chem Phys 2001. [DOI: 10.1063/1.1364680] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Interdisciplinary Applications of Pauling's Metallic Orbital and Unsynchronized Resonance to Problems of Modern Physical Chemistry: Conductivity, Magnetism, Molecular Stability, Superconductivity, Catalysis, Photoconductivity, and Chemical Reactions. J Phys Chem A 2000. [DOI: 10.1021/jp0018549] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Respiratory failure during induction chemotherapy for acute myelomonocytic leukaemia (FAB M4Eo) with ara-C and all-trans retinoic acid. Br J Haematol 2000; 109:847-50. [PMID: 10929040 DOI: 10.1046/j.1365-2141.2000.02043.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report two cases of acute myeloid leukaemia FAB classification M4Eo with high white cell counts at presentation, who developed acute respiratory failure with pulmonary infiltrates on chest radiograph soon after commencing conventional cytotoxic chemotherapy plus all-trans retinoic acid (ATRA). We suggest that in patients with M4Eo ATRA should be used with caution, perhaps delaying its commencement until the white cell count is < 10 x 109/l.
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Cyclopentadiene stability: Quantum Monte Carlo, coupled cluster, and density functional theory determinations. Mol Phys 1999. [DOI: 10.1080/00268979909482999] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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A second case of Corynebacterium pseudotuberculosis in New Zealand. THE NEW ZEALAND MEDICAL JOURNAL 1997; 110:469-70. [PMID: 9451415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Reducing perinatal mortality in lambs. Vet Rec 1997; 140:136. [PMID: 9042700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Quantum Monte Carlo determination of the lithium 2 (2)S-->2 (2)P oscillator strength: Higher precision. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1995; 51:2049-2052. [PMID: 9911817 DOI: 10.1103/physreva.51.2049] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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Molecular reorientation cross sections in collisions of He(1S)+D2(B 1Σ+u), HD(B 1Σ+u). J Chem Phys 1994. [DOI: 10.1063/1.468484] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Molecular states of CO interaction with 3d-metal surfaces. PHYSICAL REVIEW. B, CONDENSED MATTER 1994; 50:1868-1873. [PMID: 9976377 DOI: 10.1103/physrevb.50.1868] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Random‐walk approach to mapping nodal regions of N‐body wave functions: Ground‐state Hartree–Fock wave functions for Li–C. J Chem Phys 1992. [DOI: 10.1063/1.463296] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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49
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Optimization of a multideterminant wave function for quantum Monte Carlo: Li2 (X 1Σ+g). J Chem Phys 1992. [DOI: 10.1063/1.462043] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Theoretical study of the CO interaction with the Fe(100) surface. PHYSICAL REVIEW. B, CONDENSED MATTER 1991; 44:1910-1913. [PMID: 9999731 DOI: 10.1103/physrevb.44.1910] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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