Amsterdam density function calculation bonding

Valence bond (VB) theory may be used as an alternative to molecular orbital (MO) theory for computational organotin studies. Most MO calculations of organotin systems use Gaussian, GAMESS, or Amsterdam density functional (ADE) program suites. A variety of VB methods exist, and although VB wavefunctions are more difficult to calculate, some VB methods can also be implemented in these programs. ... 

The Amsterdam Density Functional (ADF) method [118,119] was used for calculations of some transactinide compounds. In a modem version of the method, the Hamiltonian contains relativistic corrections already in the zeroth order and is called the zero-order regular approximation (ZORA) [120]. Recently, the spin-orbit operator was included in the ZORA Fock operator [121]. The ZORA method uses analytical basis fimctions, and gives reliable geometries and bonding descriptions. For elements with a very large SO splitting, like 114, ZORA can deviate from the 4-component DFT results due to an improper description of the pi/2 spinors [117]. Another one-component quasirelativistic scheme [122] applied to the calculations of dimers of elements 111 and 114[116,117]isa modification of the ZORA method. 

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