Abstract
An algorithm for the efficient computation of molecular electrostatic potential is reported. It is based on the partition/expansion of density into (pseudo) atomic fragments with the method of Deformed Atoms in Molecules, which allows to compute the potential as a sum of atomic contributions. These contributions are expressed as a series of irregular spherical harmonics times effective multipole moments and inverse multipole moments, including short-range terms. The problem is split into two steps. The first one consists of the partition/expansion of density accompanied by the computation of multipole moments, and its cost depends on the size of the basis set used in the computation of electron density within the Linear Combination of Atomic Orbitals framework. The second one is the actual computation of the electrostatic potential from the quantities calculated in the first step, and its cost depends on the number of computation points. For a precision in the electrostatic potential of six decimal figures, the algorithm leads to a dramatic reduction of the computation time with respect to the calculation from electron density matrix and integrals involving basis set functions.
Highlights
Despite of its undeniable success in the description of chemical structure and reactivity, the language of chemistry is largely grounded on concepts with loose theoretical foundations
These results have been compared with the molecular electrostatic potential (MESP) exact values, V exact, computed using the electron density matrix and the integrals involving basis set functions: V exact =
Where ρrs are the elements of the density matrix, and nbasis stands for the number of basis functions, χr, in the Linear Combination of Atomic Orbitals framework (LCAO) calculation
Summary
Despite of its undeniable success in the description of chemical structure and reactivity, the language of chemistry is largely grounded on concepts with loose theoretical foundations. Because of the weak arguments that supported his model, his work was promptly followed by attempts to overcome its theoretical shortcomings by providing a more rigorous foundation based on the recently discovered quantum mechanics In these attempts, many concepts were proposed to underpin Lewis ideas by pioneers like Coulson, Pauling, Hückel and Mulliken, just to mention some of the most conspicuous figures. Many concepts were proposed to underpin Lewis ideas by pioneers like Coulson, Pauling, Hückel and Mulliken, just to mention some of the most conspicuous figures Their early efforts to accommodate the complex and sometimes elusive chemical facts in the frame provided by the new emerging physics were driven in part by the available computational capabilities, that were very reduced at the time
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