Analytical calculation of atomic and molecular electrostatic potentials from the Poisson equation
TL;DR: In this paper, an analytic formulation for the total potential in atomic and molecular systems, based on the electrostatic approach from the Hellmann-Feynman theorem, is given.
About: This article is published in Chemical Physics Letters.The article was published on 1973-07-01. It has received 79 citations till now. The article focuses on the topics: Poisson's equation & Laplace's equation.
Citations
More filters
TL;DR: In this article, it is demonstrated that semi-empirical methods give electrostatic potential (ESP) derived atomic point charges that are in reasonable agreement with ab initio ESP charges.
Abstract: It is demonstrated that semiempirical methods give electrostatic potential (ESP) derived atomic point charges that are in reasonable agreement with ab initio ESP charges. Furthermore, we find that MNDO ESP charges are superior to AM1 ESP charges in correlating with ESP charges derived from the 6-31G* basis set. Thus, it is possible to obtain 6-31G* quality point charges by simply scaling MNDO ESP charges. The charges are scaled in a linear (y = Mx) manner to conserve charge. In this way researchers desiring to carry out force field simulations or minimizations can obtain charges by using MNDO, which requires much less computer time than the corresponding 6-31G* calculation.
2,948 citations
TL;DR: In this paper, a model that relies on the knowledge of the molecular electrostatic potential, which is derived from a molecular wave function by using the usual methods for calculating the mean expectation value of an operator, is discussed.
Abstract: Publisher Summary This chapter discusses a model that relies on the knowledge of the molecular electrostatic potential, which is derived from a molecular wavefunction by using the usual methods for calculating the mean expectation value of an operator. In its basic premises the model employs quantum mechanics, with only the approximations necessary in molecular quantal calculations. The model is also discussed regarding its relationships with the Hellmann–Feynman theorem. The electrostatic potential V itself is examined in order to show how the electrostatic potential reflects the characteristics of the electronic distribution of a molecule and then the reliability of V is discussed as a reactivity index. The shape of the electrostatic potential and its relationship to the electronic molecular structure is discussed with the aid of various examples. One of them includes the glycine tautomers and the corresponding anion example. The chapter also discusses the electrostatic molecular potential in terms of local group contributions.
1,116 citations
TL;DR: A large number of chemical and biochemical systems and processes have now been studied in terms of electrostatic potentials, referring specifically to the polycyclic aromatic hydrocarbons and halogenated olefins and their epoxides.
Abstract: The electrostatic potential V(r) that is created in the space around a molecule by its nuclei and electrons (treated as static distributions of charge) is a very useful property for analyzing and p...
593 citations
TL;DR: In this article, an efficient algorithm for the evaluation of molecular electrostatic potential (ESP) is proposed, which regroups the expression in terms of primitive Gaussian type orbitals (GTOs) with identical angular momentum types and nuclei centers.
Abstract: The evaluation of molecular electrostatic potential (ESP) is a performance bottleneck for many computational chemical tasks like restrained ESP charge fitting or quantum mechanics/molecular mechanics simulations. In this paper, an efficient algorithm for the evaluation of ESP is proposed. It regroups the expression in terms of primitive Gaussian type orbitals (GTOs) with identical angular momentum types and nuclei centers. Each term is calculated using a computerized optimized code. This algorithm was integrated into the wavefunction analysis program Multiwfn and was tested on several large systems. In the cases of dopamine and remdesivir, the performance of this algorithm was comparable to or better than some popular state-of-the-art codes. For meta1–organic framework-5, where the number of GTOs and ESP points is 4840 and 259 262, respectively, our code could finish the evaluation in 1874 seconds on ordinary hardware. It also exhibits good parallelization scaling. The source code of this algorithm is freely available and can become a useful tool for computational chemists.
336 citations
TL;DR: An efficient microwave-assisted synthesis of new (Z)-5-arylidenerhodanines under solvent-free conditions is described and their in vitro antifungal activity was evaluated following the CLSI guidelines against a panel of both standardized and clinical opportunistic pathogenic fungi.
180 citations
References
More filters
TL;DR: In this article, a least square representation of Slater-type atomic orbitals as a sum of Gaussian-type orbitals is presented, where common Gaussian exponents are shared between Slater−type 2s and 2p functions.
Abstract: Least‐squares representations of Slater‐type atomic orbitals as a sum of Gaussian‐type orbitals are presented. These have the special feature that common Gaussian exponents are shared between Slater‐type 2s and 2p functions. Use of these atomic orbitals in self‐consistent molecular‐orbital calculations is shown to lead to values of atomization energies, atomic populations, and electric dipole moments which converge rapidly (with increasing size of Gaussian expansion) to the values appropriate for pure Slater‐type orbitals. The ζ exponents (or scale factors) for the atomic orbitals which are optimized for a number of molecules are also shown to be nearly independent of the number of Gaussian functions. A standard set of ζ values for use in molecular calculations is suggested on the basis of this study and is shown to be adequate for the calculation of total and atomization energies, but less appropriate for studies of charge distribution.
3,723 citations
TL;DR: In this paper, LCAO SCF MO calculations with minimum basis sets of Slater-type orbitals were performed for some three-membered ring compounds and a reinterpretation of the resulting wavefunctions in terms of localized (exclusive) orbitals was presented and discussed: the bent bonds in the rings are closely evidenced.
Abstract: LCAO SCF MO calculations with minimum basis sets of Slater‐type orbitals are performed for some three‐membered ring compounds. A reinterpretation of the resulting wavefunctions in terms of localized (exclusive) orbitals is presented and discussed: The bent bonds in the rings are closely evidenced. The electrostatic potentials produced in the neighboring space by the nuclear and electronic charge distributions are evaluated and employed to evidence the molecular sites more likely subject to electrophilic attacks.
354 citations
TL;DR: The concept of intramolecular binding is given a precise definition in a way that relates binding to the forces acting on the nuclei in a diatomic molecule and the space around theuclei may be separated into binding and antibinding regions.
Abstract: The concept of intramolecular binding is given a precise definition in a way that relates binding to the forces acting on the nuclei in a diatomic molecule. A consequence of the definition is that the space around the nuclei may be separated into binding and antibinding regions. These regions are described and they depend on the Coulomb law of force and on the ratio of the nuclear charges: the internuclear distance is simply a scale parameter. The influence of a single electron on the binding due to other electrons is briefly discussed.
259 citations
TL;DR: In this paper, the electrostatic potentials arising from ab initio MO LCAO GTO SCF wave functions for adenine, thymine and cytosine are given and discussed.
Abstract: The electrostatic potentials arising from ab initio MO LCAO GTO SCF wave functions for adenine, thymine and cytosine are given and discussed. Well defined characteristic regions of immediate chemical significance are found. The analysis of such results aims at comparing different protonation sites in the same molecule as well as in different ones. Differences among the proton affinities of the nitrogen atoms (pyridine-like, amine and imine) are evidenced, as well as the distinction between oxygen and nitrogen atoms.
153 citations
TL;DR: In this article, a series of single-determinant SCF-LCAO-MO wavefunctions were used to study the changes that occur in the electron density as the Hartree-Fock solution is approached.
Abstract: Electron density maps and their appropriately weighted analogs (e.g., dipole‐weighted density map) are found to provide a consistent and useful tool for the analysis and the comparison of atomic and molecular charge distributions obtained with different wavefunctions. Specific applications are made to hydrogen fluoride, for which a series of single‐determinant SCF—LCAO—MO wavefunctions permit a study of the changes that occur in the electron density as the Hartree—Fock solution is approached. An examination of alternative basis‐set functions of essentially the same size and the same energy shows that significantly different charge distributions can result; this points out the need for a careful selection of basis functions in large scale molecular calculations. It is found also that the charge density fluctuations from one basis set to another can be as large as the effects of chemical binding. Comparisons between density‐map and population‐analysis results indicate that considerable caution must be used in employing the latter for the interpretation of complicated wavefunctions.Various methods for summarizing wavefunctions in terms of characteristic parameters of the charge distribution are considered. The forces acting on the nuclei are analyzed in relation to the Hellmann‐Feynman theorem and a necessary condition on the exact molecular Hartree—Fock solution is obtained. Although none of the presently available wavefunctions for HF and LiF satisfy the condition to a high degree of accuracy, refinements in the wavefunctions are shown to yield improved results.
126 citations