Ground state energy, electronic and chemical properties: an investigation of linear acenes (n=1 to 7) linked thiophene for organic electronic material

We report a theoretical study of linear acene (n=1 to 7) linked thiophene functionality. The total ground state energies, HOMO-LUMO energy gap, frontier orbitals energies, electron affinity and ionization potential are calculated at DFT-B3LYP/6-311G* and MP2/6-311G* exchange level of the theory and basis set. The results show a good agreement when compared with the theoretical and experimental values. It is found that total ground energy of the system, HOMO-LUMO gaps energy, electrophilicity, electronegativity and chemical hardness decrease with the increasing number of electrons or acenes ring. The global chemical indices; electronegativity (χ) , electrophilicity (ɷ) and chemical hardness (ɳ) is observed to decrease as the number of electrons in acenes ring increase, whereas softness(S) and chemical potential (µ) increases with the increasing number of electrons around molecules. Also, the frontier orbital energies, Ionization energies, and electron affinity results show an improvement as compared to the acenes molecules

Theoretical investigations of β-tricalcium

Beta-tri-calcium phosphate (β-TCP) materials have gained a great deal of research considerations in biomaterial area due to their excellent biocompatibility and identical chemical compositions to the natural teeth and bones. Therefore, the β-TCP compound can be used as coatings, cement and composites as well as biocompatible ceramics for medical and dental applications. Electronic and optical properties for β-TCP compound have been investigated using density functional theory (DFT). For the calculations, we used full potential linear augmented plane wave method (FPLAPW), within three types of approximations along with local density approximations (LDA), generalized gradient approximations (GGA) and Modified Becke-Johnson (mBJ) to get the effect of the exchange and correlation in our calculations to get an accurate results. The computed band gap values for (β-TCP) compound using LDA, GGA, and mBJ-GGA approximations are 5.5 eV, 5.9 eV and 6.8 eV respectively. This is also predicted that the chemical bonding in this compound is a kind of combination of covalent and ionic character that is in a line with the experimental findings. The optical parameter, static dielectric constant ε1(0) reaches the values of 3.23681 (eV) at 0 GPa for the β-TCP compound. The obtained results are of vital nature for rising the quality of the electronic and optical properties of this material, and provide more evidence to fabricate novel Beta-Tri-calcium phosphate biomaterials for medical and dental applications

Density functional theory study of the electronic and optical properties of pure and magnesium doped Β-tricalcium phosphate compound

β-Tri-calcium phosphate material (β-TCP), have attract a wide interest in the material science and medical science applications, due to its excellent biocompatibility and its identical chemical compositions to the natural teeth and bones. For that reason, (β-TCP) compound is widely used as biocompatible ceramics in medical and dental science applications. However, research shows that, pure β-TCP material has lower ability to stimulate the growth of natural bone and teeth as needed. Therefore, in order to address this deficiency magnesium impurity is used to replace calcium in the matrix of pure β-TCP to enhance its electronic and optical properties which are not present in the pure one. Thereby, its biological performance becomes improved. By changing the chemical composition of β-TCP to be similar to the mineral compositions of the natural teeth and bones. This will give more insight in fabrication of biomaterial devices for replacing, repairing and rebuilding the broken or damaged human teeth and bones. Here, we present the study of compound β-TCP using density functional theory (DFT). For the calculations, we used full potential linear augmented plane wave method (FPL-APW), along with generalized gradient approximations (GGA) potential. The band gap values of 5.2 eV and 3.4 eV are obtained for the pure and Mg-doped β-TCP, respectively. These results are in good agreement with the experimental values. Our results show peaks which correspond to the refractive index, complex dielectric function, optical conductivity, optical reflectivity, extinction coefficient, absorption efficient, and electron energy loss. These peaks are shifted towards the higher energy values for the pure and Mg-doped β-TCP material. The obtained results have more significance for increasing the quality of electronic and optical properties of this material and offer more evidences to synthesize enhanced β-TCP material for dental and medical applications

Local electronic and electrical properties of functionalized graphene nano flakes

Based on experimental findings models of amorphous graphene related carbon materials were generated using graphene nano flakes. On the optimized structures detailed local electronic properties were investigated using density functional theory. The electrical conductivities of all these models were also estimated using an in-house program based on tight-binding method. The calculated electrical conductivity values of all the models agreed well with the trend of calculated energy gap and graphitic character

Efficiency enhancement of dye-sensitized TiO2 solar cell based on ruthenium(II) terpyridyl complex photosensitizer

We theoretically investigated the influence of the ligands on the enhancement of the efficiency toward absorption in the solar spectrum of ruthenium(II) terpyridyl complex. In the present work, the NCS ligands of the parent black dye 4,4′,4″-tricarboxy-2,2′:6′,2″-terpyridine)ruthenium(II) complex (BD0) were kept unchanged, while π-conjugating spacers were introduced between the terpyridine ligands and the anchoring groups -COOH. Molecular structures, electronic, and spectroscopic properties of four designed black dyes, in addition to the parent black dye (BD0), were examined. Compared with the parent black dye BD0, broad and intense absorption bands in the infrared and near-infrared region (red-shifted) were found, featuring the enhancement of the absorption efficiency resulting from the insertion of the proposed π-conjugating spacers