Comparison of ab initio and density functional calculations of electric field gradients:: The 57Fe nuclear quadrupole moment from Mossbauer data

被引:43
作者
Schwerdtfeger, P
Söhnel, T
Pernpointner, M
Laerdahl, JK
Wagner, FE
机构
[1] Univ Auckland, Dept Chem, Auckland, New Zealand
[2] Vrije Univ Amsterdam, Fac Sci, Dept Theoret Chem, NL-1081 HV Amsterdam, Netherlands
[3] Univ Oslo, Dept Chem, N-0315 Oslo, Norway
[4] Tech Univ Munich, Phys Dept E15, D-85747 Garching, Germany
关键词
D O I
10.1063/1.1398095
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The difficulty in accurate determination of the nuclear quadrupole moment of the first I=3/2 excited nuclear state of Fe-57 from electronic structure calculations of the iron electric field gradient combined with Mossbauer measurements of the nuclear quadrupole splitting in the isomer shift is addressed by comparing ab initio with density functional calculations for iron pentacarbonyl, Fe(CO)(5), ferrocene, Fe(C5H5)(2), and the (5)Delta (g) electronic ground states of FeCl2 and FeBr2. While the ligand field gradient tensor components change relatively little with the method applied, the iron electric field gradient is sensitive to the specific density functional used. Single reference many-body perturbation theory for electron correlation also performs poorly for the iron electric field gradient and shows extreme oscillatory behavior with a change in the order of the perturbation series. Even with larger basis sets and coupled cluster techniques a precise value for the iron electric field gradient could not be determined from electronic structure calculations due to limitations in the theoretical procedures. In order to avoid uncertainties in the measured isomer shift which enters into the nuclear quadrupole coupling constant we determined the Mossbauer spectrum of Fe(C5H5)(2) between temperatures of 4.2 and 295 K. In this range two phase transitions are observed, but the quadrupole splitting is not very dependent on the solid state structure in each phase. Solid state effects for the Fe(CO)(5) are determined by comparing the iron electric field gradient of the isolated molecule with the value obtained from first principle solid state calculations at various levels of theory. These calculations show that the influence of near neighboring effects to the iron electric field gradient is small. Fully relativistic Dirac-Hartree-Fock calculations for Fe(CO)(5) reveal that relativistic effects for the iron electric field gradient are small as well. Fe(CO)(5) is therefore an ideal test molecule for the determination of an accurate nuclear quadrupole moment from electronic structure calculations if combined with an experimental nuclear quadrupole coupling constant. Our best estimate for the Fe-57 nuclear quadropole moment is 0.14(2) barn in reasonable agreement with recent nuclear structure calculations. (C) 2001 American Institute of Physics.
引用
收藏
页码:5913 / 5924
页数:12
相关论文
共 109 条
[32]   ELECTRIC-FIELD GRADIENT AND ELECTRONIC-STRUCTURE OF LINEAR-BONDED HALIDE COMPOUNDS [J].
ELLIS, DE ;
GUENZBURGER, D ;
JANSEN, HB .
PHYSICAL REVIEW B, 1983, 28 (07) :3697-3705
[33]   van der Waals bonds in density-functional theory -: art. no. 032502 [J].
Engel, E ;
Höck, A ;
Dreizler, RM .
PHYSICAL REVIEW A, 2000, 61 (03) :5
[34]   Microscopic environment of Fe in epitaxially stabilized c-FeSi [J].
Fanciulli, M ;
Weyer, G ;
Svane, A ;
Christensen, NE ;
von Känel, H ;
Müller, E ;
Onda, N ;
Miglio, L ;
Tavazza, F ;
Celino, M .
PHYSICAL REVIEW B, 1999, 59 (05) :3675-3687
[35]   The electronic configuration of Fe in beta-FeSi2 [J].
Fanciulli, M ;
Rosenblad, C ;
Weyer, G ;
Svane, A ;
Christensen, NE ;
vonKanel, H ;
Rodriguez, CO .
JOURNAL OF PHYSICS-CONDENSED MATTER, 1997, 9 (07) :1619-1630
[36]   Exchange-correlation density functional beyond the gradient approximation [J].
Filatov, M ;
Thiel, W .
PHYSICAL REVIEW A, 1998, 57 (01) :189-199
[37]  
FRISCH MJ, 1999, GAUSSIAN 98
[38]   Density functional study of the Fe-CO bond dissociation energies of Fe(CO)5 [J].
González-Blanco, O ;
Branchadell, V .
JOURNAL OF CHEMICAL PHYSICS, 1999, 110 (02) :778-783
[39]  
GREATREX R, 1969, DISCUSS FARADAY SOC, P126, DOI 10.1039/df9694700126
[40]   MOLECULAR-STRUCTURE AND BONDING IN THE 3D METALLOCENES [J].
HAALAND, A .
ACCOUNTS OF CHEMICAL RESEARCH, 1979, 12 (11) :415-422