GAPT

For large molecules, computation time becomes a consideration. Orbital-based techniques, such as Mulliken, Lowdin, and NBO, take a negligible amount of CPU time relative to the time required to obtain the wave function. Techniques based on the charge distribution, such as AIM and ESP, require a sig-nihcant amount of CPU time. The GAPT method, which was not mentioned above, requires a second derivative evaluation, which can be prohibitively expensive. 

GAPT (generalized atomic polar tensor) a charge calculation method GB/SA (generalized Born/surface area) method for computing solvation effects... 

Such a matrix is not independent on the coordinate system, but the trace is. Cioslowski has proposed a definition of atomic charges as one-third of the trace over the APT, denoted Generalized Atomic Polar Tensor (GAPT) charges.The charge on atom A is defined as... 

The important field of ionic liquids, in most cases 1,3-dimidazolium salts (143) has been studied by IR and Raman spectroscopies supported by B3LYP calculations. Additionally, calculations of the heteroaromaticity (HOMA index) showed that cation formation causes a decrease of the aromaticity of the imidazole ring. However, when the R groups at positions 1,3 are benzyl or adamantyl, the aromatic nature of the heterocyclic moiety increases. Moreover, the electron distribution performed using the GAPT method indicated the positive charge delocalization in the imidazolium ring [143],... 

Generalized Atomic Polar Tensor (GAPT), for Hiickel theory, 93, 94 atomic charges. 226... 

In mammals, there are atleast27 Ga-, 5 G r, and 13 GT-subtypes (171) hence, the intracellular propagation of GPCR signaling is orchestrated by myriad GaPT combinations. On the basis of the primary sequence of the Ga-subunits, G proteins can be divided into different major families, including Gs, G, Gq, and G12... 

Table 8 Basis Set Dependence of Mulliken and GAPT Charges ° ...

The GAPT charges are also insensitive to basis set improvements beyond the split-valence sets. Table 8 lists the GAPT and Mulliken charges for a variety of small molecules using the STO-3G, 4-31G, and 6-31G " basis sets. Only very small difference between the 4-3IG and 6-3IG" GAPT charges are evident. 

Compound Atom GAPT charge Topological charge ... 

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