Ab initio metadynamics simulations of oxygen/ligand interactions in organoaluminum clusters

2014 ◽  
Vol 141 (14) ◽  
pp. 144304 ◽  
Author(s):  
Sufian Alnemrat ◽  
Joseph P. Hooper
Keyword(s):  
Ab Initio ◽  
Oxygen Ligand ◽  
Ligand Interactions

Nuclear Quadrupole Interactions in Cadmium Complexes: Semiempirical and ab initio Calculations

1999 ◽  
Vol 54 (6-7) ◽  
pp. 422-430 ◽  
Author(s):  
Lars Hemmingsen ◽  
Ulf Ryde ◽  
Rogert Bauer
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Semiempirical Calculations ◽  
Semiempirical Model ◽  
Hydrogen Atoms ◽  
Cadmium Complexes ◽  
Quadrupole Interactions ◽  
Nuclear Quadrupole Interactions ◽  
Ligand Interactions ◽  
Nuclear Quadrupole

Abstract Semiempirical calculations, based on the so-called angular overlap model, have been compared with ab initio methods (MP2) for the calculation of nuclear quadrupole interactions (NQI’s) in cadmium complexes with biologically relevant ligands (H2O, OH-, cysteinate, carboxylate, and imidazole). The assumptions on which the semiempirical model is based have been tested and the comparison indicates that: 1) A change in the Cd-ligand bond length by 0.1 A may change the electric field gradient (EFG) by about 0.2 a. u.. A simple scheme to incorporate such effects in the semiempirical method is suggested. 2) The effect of ligand-ligand interactions is up to about 0.2 a. u. for the largest diagonal element of the EFG tensor for the tested complexes, and such effects can significantly influence the so-called asymmetry parameter. 3) The position of non-coordinating atoms on the ligands can in some cases (e. g. the hydrogen atoms of water) significantly influence the EFG. The combined effect of non-coordinating atoms and ligand-ligand interactions may cause deviations of up to 0.35 a.u. between ab initio and the semiempirical calculations. 4) In the semiempirical model each ligand is characterised by one parameter, the so-called partial nuclear quadrupole interaction. This parameter has been evaluated by ab initio calculations, and agreement was found within about 0.2 a. u. (≈ 40 Mrad/s) for all ligands except imidazole. 5) A change in the coordination number from 2 to 6 may change the partial NQI by about 0.3 a. u.

Ab Initio Investigation of Gadolinium Complexes with Polyamino Carboxylate Ligands and Force Fields Parametrization of Metal−Ligand Interactions

1998 ◽  
Vol 102 (24) ◽  
pp. 4606-4614 ◽  
Author(s):  
Ugo Cosentino ◽  
Giorgio Moro ◽  
Demetrio Pitea ◽  
Alessandra Villa ◽  
Pier Carlo Fantucci ◽  
...  
Keyword(s):  
Ab Initio ◽  
Force Fields ◽  
Carboxylate Ligands ◽  
Gadolinium Complexes ◽  
Ligand Interactions ◽  
Metal Ligand

Identifying Receptor−Ligand Interactions through an ab Initio Approach

2008 ◽  
Vol 112 (4) ◽  
pp. 1290-1292 ◽  
Author(s):  
Pablo F. Salazar ◽  
Jorge M. Seminario
Keyword(s):  
Ab Initio ◽  
Receptor Ligand ◽  
Ligand Interactions ◽  
Ab Initio Approach
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