Gasteiger charges

Here, and Lj are local indices having the form shown in Eq. (5), where lo is a constant characterizing the ith atom (in some cases the atom valence can be used to this end), Nh is the number of attached hydrogen atoms and is the charge density calculated by some fast method such as the Marsili-Gasteiger charge calculation method [7]. 

Gasteiger J and M Marsili 1980. Iterative Partial Equalization of Orbital Electronegativity - Rapid Access to Atomic Charges. Tetrahedron 36 3219-3288. 

PROAIM PEOE Methods for Charges Gasteiger, Scheraga, Gombar (HDI)... 

Gasteiger, J., Marsili, M. Iterative partial equalization of orbital electronegativity - a rapid access to atomic charges. Tetrahedron 1980, 36, 3219-3228. 

An example of quantum mechanical schemes is the oldest and most widely used Mulliken population analysis [1], which simply divides the part of the electron density localized between two atoms, the overlap population that identifies a bond, equally between the two atoms of a bond. Alternatively, empirical methods to allocate atomic charges to directly bonded atoms in a reasonable way use appropriate rules which combine the atomic electronegativities with experimental structural information on the bonds linking the atoms of interest. A widely used approach included in many programs is the Gasteiger-Hiickel scheme [1]. 

This part of the case study was broken into two sections, the original descriptor set (2,125,127) (Hansch descriptors) and a new set of descriptors calculated in MOE (6) (MOE descriptors). The MOE Descriptors were calculated for molecules assigned Gasteiger (70) partial charges in the MMFF (46-52). The new descriptor set is constructed of three properties. The water accessible surface area (ASA) calculated using a radius of 1.4 A for a water molecule and the... 

Using SOMFA2 (11), QSAR models were constructed based on shape and electrostatic potential [Gasteiger (70) and MMFF (46-52) partial charges] for... 

This portion of the case study demonstrated that partial charges could be incorrect for certain chemical systems. Quantum mechanical calculations were only used to determine which model was correct not to perform the actual calculations. Several of the models were re-evaluated (data not shown) using PM5 partial charges determined in MOPAC2002 (74). The results were similar to the R2 values determined using Gasteiger partial charges. 

The 3-D artemisinin analogue database was created with Sybyl 6.2 (Tripos Assoc., St. Louis, MO)154 using the reported crystal structure for artemisinin as a template. The structures were minimized using the Tripos force field in Sybyl 6.2, producing structures close to that of artemisinin. To best describe the aromatic side chains of some analogues, as well as the aliphatic nature of the artemisinin backbone, Gasteiger-Htickel charges were calculated for each of the compounds. 

Estrogen receptor a GOLD random set from the filtered database, Gasteiger-Marsili charges 10 10(10) 10 1 ... 

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