اسم المؤلف:
مالك حسين علي العلوش العامري
اسم المشرف:
نغم شاكر تركي العوادي
المستخلص:
تم استخدام حسابات ميكانيك الكم التقريبية شبه التجريبية وفق نموذج الحساب PM3)) وحسابات ميكانيك الكم الاساسية التامة غير التقريبية وفق نظرية دوال الكثافة (DFT) وباسلوب B3LYP وعناصر قاعدة 6 - 311G لحساب جزيئة الفلرين التي امتلكت التماثل Ih مع وحدات بناءها (5 | Semi - empirical quantum mechanical methods (PM3) and Density Functional theory calculations (DFT/ B3LYP/ 6 - 311G) were executed to evaluate the fullerene molecule ,the internal coordinates (bond length and angles) and some physical and energetic properties.Calculations of the geometrical Parameters (bond lengths and bond angles), have shown that the (C=C) bond length is increased with increasing the size of the molecule that increased elasticity especially to fullerene to be like a ball. The (C - C) bond length is decreased with increasing the size of molecule, that means fullerene will be more stable than the other molecules.The energetic values (heat of formation) is found to be increased with the increasing of the size of molecule. The total energy is decreased with increasing size of molecule that means the stability will increase with the increasing of the size of unit construction of fullerene molecule , on the other hand , the energetic difference (E HOMO - LUMO) between the higher level of orbital and the lower level of orbital are decreased with the increasing of the size of molecule ' unit construction reaching to the fullerene molecule. So, this property will increase the significance of fullerene in the industrial and the electrical purposes.The vibrational modes frequencies with ( 3N - 6) whereas N is represented by number of molecule atoms which are evaluated with the absorption intensities of infrared frequencies. symmetrical and coordinated modes were discussed at the equilibrium geometric formation by using the programs MOPAC & Gaussian 05.It is worthy to say that it was not mentioned before that the complementary classification for the vibrated motion modes for such molecules , so our evaluations may considered unique. It is noted , as well , that CH stretching frequency has had fluctuations that means increasing and decreasing in the values of frequencies. In connected with the bending vibrated modes which taking place out of plane of the molecule are decreased with the increasing size of the unit constructions of molecule but it is increased only at the fullerene molecule. Conversely, the bending vibrated modes which are taken place in the plane of molecule are increased with the increasing the size of unit construction of molecule but are decreased at the fullerene molecule.The distribution of the electronic charges density on the atoms of unit construction of fullerene molecule were studied, the results shown the absence of the electronic charge on the atoms of Fullerene molecule and its concentrated at atoms of the outer circumferential edges C - Cc for the aromatic rings in its own unit construction. Semi - empirical methods (PM3) and Density Functional theory calculations (DFT/ B3LYP/ 6 - 311G) were carried out to evaluate the vibration frequencies and infra - red (IR) absorption intensities for equilibrium geometries of construction units of (6,0) zigzag (Mono (D6h), Di (D6d), Tri(D6h), Tetra (D6d)) ring layers SWCNTs and the internal coordinates ( bond length & angles ) at the equilibrium geometric formation symmetrically according to group theory were evaluated. The most important notes were axial bond length C - Ca which is decreased with the increasing of the tube length whether odd or even number of ring layers. The length of these mentioned axial bonds will be longer in the outer layers than the middle layers that means the increasing of stability of the tube with its length increasing , with the ability of replacing the external atoms of the tube because they are connected with longer and weaker bonds. The reverse was found with the circumferential bond lengths C - Cc was as they were increased with the increasing length of the tube whether the tube was odd or even in number of ring layers. Moreover , the lengths of these bonds are decreased in the middle side to the outer one for the odd and even ring layers. This will confirm the stability of the tube with its length increasing. The lengths of outer bonds C - H which are situated on the edges of the tube which were approximately fixed , with exception of the bond length of CH bonds in Mono ring layers which were longer because the large negative charge on carbon to which it is bonded and the large positive charge on it compared with the positive charge on hydrogen atoms of the multi - layers tubes. The heat of formation which was found to be increased with the increasing of the length of the tube , that means increasing of the stability and the aromatic properties , with the increasing of number of tube' layers. This property will increase the importance in the uses of these tubes for the industrial and electrical purposes as semi - conductors.The vibrational modes frequencies with 3N - 6 with the absorption intensities of infrared frequencies were evaluated and classified. These modes were discussed in symmetrical and coordinating manners at the equilibrium geometric formation, by using the programs of MOPAC and Gaussian 05 , with confirming on unavailability of bounded specification for such modes with 3N - 6 in the literature. We have a through our studies that the stretching vibration modes of symmetric and anti - symmetric Carbon - Carbon axial bond (C - Ca) increased with the increasing length of tube , and this will increase the physical properties for electrical conductivity with confirming on the significance of nanotube industrially. For the vibrational bending frequencies which are taking place in plane and out of plane of molecule surface as well as the vibrational stretching for odd number of ring layers (Mono and Tri) fluctuation will be happening in the relations , as all of them will be decreased with the increasing of tube ' length except (C - Caasym, C - Casym , ? CHsciss. , ? ringasym , ? ringsym and ? ringsym ) which be increased with the increasing the length of tube. The vibrational bending frequencies which are taking place in plane and out of plane of molecule surface for the even number of ring layers ( Di and Tetra layers ) will be decreased with the increasing of tube' length except (? CHsciss.) which is increased with the increasing of tube' length. Furthermore , all vibrational modes which are related to the puckering , breathing and bending movements of clockwise and anti - clockwise according to "group theory" were determined in accurate manner to which deformations are related , which are happened in the tubes , as a result of vibration, that may prevent the flow of electrons' movements and their transitions. The numerical values for the vibrational frequencies which are resulted from Semi - empirical methods (PM3) were acceptable in comparing with the strict calculations , hopping to achieve best values and to be close to the values obtained for the strict calculations (DFT) method to be suited with the basis and standards that are depended internationally. Some of these values were corrected by multiplied by constant scaling factors for such molecules. The results of scaling were good and very close to the experimental and calculated values.The distribution of charges' density on units of construction atoms of (6,0) zigzag nanotube SWCNTs also were studied. The results were consistent with the physical and experimental conductivity properties for such calculated tubes , as the intensity of the electronic charge was concentrated on the outer circumferential edges of atoms C - Cc for the aromatic molecules as well as for nanotubes with its disappearing form outer side towards the middle side of multi - ring layers ( Mono , Di , Tri and Tetra ).
