Quantum calculations of the interaction of cobalt, mercury, lead and aluminum ions with carbon nanotubes and boron nitride

Academic Thesis for Master's Degree

Field: Chemistry Major: Analytical Chemistry

Abstract

In recent years, the use of nanotubes as nanocarriers for drug delivery has been investigated. In this research, CNT(5-5), CNT(6-0), BNNT(6-0) and BNNT(5-5) doped Ga carbon nanotubes have been used.

First, the nanotubes were drawn by Gauss View and Nanotube Modeler software, and then calculated by Gaussian 09 software with DFT method and B3LYP/LanL2DZ basis series. And then the ions of lead (II), cobalt (II), mercury (II) and aluminum (III) were placed inside nanotubes and calculated according to the mentioned method. The results including information related to binding energy, dipole moment, atomic charges, fundamental properties (ion potential, electron affinity, chemical potential and hardness and softness) and HOMO and LUMO energy gap were calculated and evaluated and the following results were obtained. In terms of binding energy and absorption rate, CNT(5,5) nanotube has the most interaction and absorption with Pb2+ ion.

In terms of dipole moment, BNNT(5,5) doped Ga nanotube has the highest dipole moment with Al3+ ion, and CNT(5-5) nanotube structure with Al3+ ion has the lowest dipole moment.

Ionization energy values ??have shown that the Hg2+ & BNNT-Ga structure has the highest ionization energy and the Hg2+ & CNT(6,0) structure has the lowest ionization energy and the highest reactivity.

The values ??of the HOMO and LUMO gap in the ions are high before the interaction with the nanotubes and decreased after the interaction, which indicates charge transfer and increased conductivity. And among the structures after placing the ion inside them, the structure of Hg2+ & BNNT-Ga has the largest gap and the lowest conductivity. style="direction: rtl;">-1 Introduction

Bohr's atomic model, which was the most complete theory in describing the microcosm until the advent of quantum mechanics, could not make a correct statement about the rules for choosing the hydrogen atom. According to such empirically observed rules, only certain levels of energy are observed. In fact, the electron of the hydrogen atom does not have any desired energy and is only bound to certain energies. Bohr's atomic theory, which today is called the old quantum theory, had no roots in quantum mechanics and borrowed its principles from classical mechanics. However, Bohr's theory clearly showed the discontinuity of energy levels in the hydrogen atom. In this theory, in addition to energy, the amount of angular momentum was discrete. Even the space of electron movement around the bunch was limited to specific orbits with a certain distance from the nucleus. The distinction between the old quantum theory and classical mechanics was in the discreteness of quantitative values ??such as energy and angular movement. As you can see in Figure 1-1, in Bohr's theory, the electron is located on planes with a certain energy and radius from the nucleus. This theory also justified the electron not falling on the nucleus of the hydrogen atom. Because the electron can only be in certain orbits, in passing from one orbit to another, it emits energy, the amount of which is exactly equal to the energy separating these two levels from each other. At the beginning of the 20th century, new experiments began, which revealed some points about the validity and reliability of fluid mechanics. One of them was the heat capacity at constant volume and constant pressure of objects. [11, 1]

According to the classical theory and based on the principle of mutual contribution, the vibration contribution should be equal, but in practice, a large temperature dependence was observed for At first, it was Max Planck who, by assuming discrete energy values, was able to provide a satisfactory model to describe thermal radiation from a cavity. His theory was rejected because of this very strange and unusual assumption that energy has discrete values. But a few years later, Einstein showed the correctness of this assumption in a photoelectric experiment.. During an experiment that became known as the photoelectric effect, he showed that only certain amounts of energy are allowed and that energy is a discrete quantity. In this experiment, a flat metal-like surface is irradiated and its two ends are connected to two electrodes. The electric current caused by the removal of electrons causes the voltage difference to be recorded. In this experiment, light presented a behavior very different from what was known about it. [1]

According to classical mechanics, it is assumed that the energy of radiation corresponds to the intensity of radiation. Therefore, in the photoelectric experiment, it was expected that more current would be obtained by increasing the intensity of the light irradiated on the metal surface. But in practice, no change in the output current was obtained by increasing the light intensity. On the other hand, in classical mechanics, there should be no change in current intensity with increasing frequency. But it was observed that with increasing frequency and reaching a certain limit (threshold frequency), the current intensity increases. So the experiment shows that the energy depends on the frequency. Finally, Einstein proposed the following relationship to describe this phenomenon:

Here is the threshold frequency below which absorption does not occur if the radiation frequency is lower, and it is the kinetic energy of the electron exiting the surface. He suggested that light should have a non-wave behavior and should act as particles. Before that, Newton attributed the nature of particles to light. But experiments such as Young's experiment (double slit experiment) showed the wave nature of light. In Yang's experiment, when light passes through two slits side by side, a diffraction pattern is observed in the curtain, which is simply concluded from wave mechanics [1 and 8]. The basis of the discreteness of the values ??of quantities continued to grow and after its formulation in 1925 by Heisenberg and 1926 by Schr?dinger until the early 1940s, it solved so many intractable problems that it was unimaginable. Quantum mechanics is a purely statistical theory and contains many classical statistical rules. With the difference that statistics in classical mechanics was used for a set of systems and because of our ignorance of the complete state of the system, but in quantum mechanics it is used because the phenomena are statistical in nature. There are even quantum statistics for single systems. In addition, the probability in quantum mechanics does not refer to the current state of the system and is only in the case after the measurement has been performed. But in classical mechanics, it describes the probability of the current state of the system. [8]

It became known as the ultraviolet disaster. The absolute failure of classical statistical mechanics in describing the changes in short-term, medium-term and long-term adverse effects related to various types of pollution [1] water, air, soil, hazardous waste [2], heavy metals, etc. is not hidden from anyone. Today, all over the world, exorbitant costs are spent in order to control and neutralize pollutants, and it is obvious that our country will not be exempted from this due to the rapid development process. Therefore, any useful research in these fields can significantly contribute to the protection of the environment and guaranteeing people's health; At the same time, the harmful phenomenon of fine dust [3], which the provinces of the country are seriously dealing with, should not be forgotten. Therefore, such interactions have special importance in the field of environment and human health. Due to the fact that the common reactions at the nanoscale naturally occur at the molecular level, there is a precise coordination regarding the study of nanoscale particles related to natural systems on the one hand, and the laws of quantum chemistry [4] and computational chemistry [5]. [7 and 9]

The basis of quantum chemistry and computational chemistry is modeling and performing very complex, long and time-consuming calculations, based on the analysis of various types of Schr?dinger equations [6] and other advanced mathematical models in quantum mechanics, which is done through the use of high-quality and powerful computers and the use of fully specialized software, study and research in these fields.