INTRODUCTION
Selenium is one of the greatest significant and fascinating trace elements in the field of health in addition to human biology [1]. The properties of bulk selenium are to a large extent determined by Sen allotropes and aggregates. As a consequence, semiconducting selenium nanomaterials have great potential in electronics [2]. Selenium is the single element that has codon in messenger RNA which make probable its insertion into the Seleno protein in the form of seleno-cysteine[3].Carbides of transition metals form an interesting class of materials in which anions and cations are held together by a mixture of strong ionic, covalent, and metallic bonds [4].Gaussian 03 program (computer software which is capable of predicting many properties of molecules and reactions, including the molecular energies and structures) [5] to make the calculation. The present work aims to design of PVA/SeO2/SiC nanostructures to use in various electronic devices.  
              
THEORETICAL PART
Energy gap refers to energy difference between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) according to the Koopmans theorem [5]:    

Here Egap indicates the energy gap ELUMO, and EHOMO denoted the energies of HOMO and LUMO in consecution.
Ionization Potential energy (IP) is defined as the minimum energy required to remove an electron from the atom in a gaseous phase. Ionization energy is expressed in units of electron Volt (eV) [6].

Electron affinity can be defined as the energy released upon attachment of an electron to an atom or molecule resulting in the formation of the negative ion [5]. 

One of the global quantities is chemical potential (μ); it measures the escaping tendency of an electronic cloud. is related to two known quantities, IE and EA, as in the following relationship [7].

Chemical hardness is the resistance of a species to lose electrons, for insulator and semiconductor, hardness is half of the energy gap. we can calculate the chemical hardness (H) [8]:       
                              

                                                                                                
Chemical softness  is the inverse with hardness as below equation [9]:

Electrophilicity can be defined as a measure of energy lowering due to maximal electron flow between donor and acceptor [10]: 
                                

                                                                                                           
R. Mulliken defined electronegativity as the average of the ionization energy and electron affinity as follows [9]:   

                                                                                   
The electric dipole polarizability is the measure of the linear response of the electron density in the presence of an infinitesimal electric field F and it represents a second order variation in energy. The polarizability is calculated as the main value as given in the following equation [11,12].  

RESULTS AND DISCUSSION
Fig. 1 shows find the relaxation of the molecule, in which the optimized structure of the molecule is the structure at minimum energy, and it is performed by finding the first derivative of the energy with respect to distance between different atoms. Table 1 represents the standard orientation of all atoms in the molecule. The bonds values in present work are in a well agreement with previous theoretically studies [2,13,14].
Fig. 2 shows the IR-Spectrum of (PVA-SeO2-SiC) (90Atom)composites using DFT.It has been found that the strong peak observed at (2800cm-1) is attributed to the (O-H) groups.
In Raman spectroscopy, a change is experiential in the polarization of molecules; that is, a visible or ultraviolet photons interacts with the vibrating molecular bonds, gaining or losing part of their energy, thereby generating the spectrum [15]. Fig. 3 shows the Raman spectra of (PVA-SeO2-SiC) (90Atom) composites. Strengths of Raman spectra depend on the probability that photon with particular wavelength will be absorbed.
Fig. 4 show the UV-Vis spectra Visible and Ultra Violet spectrum is dependent on upon the electronics structure of the molecule. The UV-Vis calculations of the (PVA-SeO2-SiC) (90Atom) composites studied from the B3LYP-TD/LanL2DZ method included the excitation energy, wavelength, oscillator strength and electronic transition. 
Table 2 represents the energy gap of (PVA-SeO2-SiC) (90Atom) composites and compared with the experimental data in Ref [16,14]. Fig. 5 illustrates the3-D distribution of HOMOs and LUMOs for the studied structures. The visualization of HOMO – LUMO obviously characterizes the electron cloud in occupied and virtual orbital. The green color cloud shows the HOMO and red color shows the LUMO electrons in SeO2 nanostructures. DOS spectrum, the charge density is low in occupied orbital and high in virtual orbital for pure, O and H substituted SeO2 nanostructures. This mentions the localization of charges along the virtual orbitals than in occupied orbitals.     
Fig. 6 illustrates the electrostatic surfaces potential (ESP) distribution of structures calculated from the total self-consistent field SCF. ESP distributions of structure are caused by repulsive forces or by attracting regions around each structure. In general, the ESP surfaces of (PVA-SeO2-SiC) (90Atom) composites are dragged toward the negative charges positions in the each molecule bases the high electronegativity oxygen atoms [3.5 eV].
Table 3 shows the results of the ground state energy ET in a. u and some electronic properties of (PVA-SeO2-SiC) (90Atom) composites calculated at the same level of theory. These properties are included the ionization energy IE, electron affinity EA, electronegativity , electrochemical hardness H and electrophilic index ω [16].
Table 4 shows the average Polarizability αave and it is components in a.u of (PVA-SeO2-SiC) (90Atom) composites.
The density of states of (PVA-SeO2-SiC) (90Atom) composites as a function of energy levels were calculated by using the DFT-B3LYP/LanL2DZ level of theory. Fig. 7 shows the degenerate states as a function of energy levels for the studied structure, this degeneracy produced by the existence of the new types of atoms, and that leads to changing the bond lengths and angles or changing the geometry of the structure. 
The gauge-including atomic orbitals (GIAO) method issued to calculate the absolute shielding constants (in ppm) of (PVA-SeO2-SiC) (90Atom). Calculation gave the calculated1Hchemical shifts (in ppm) of structures. Fig. 8 1H NMR spectra of (PVA-SeO2-SiC) (90Atom) and compared with the experimental data in Ref [17].

CONCLUSION
In this paper, design, structural, optical and electronic properties of PVA/SeO2/SiC nanostructures to use in different electronics fields. Good relax of the (PVA-SeO2-SiC) (90Atom) was obtained by B3LYP-DFT at Gaussian 09 package of program and agree with that relax done by using the LanL2DZ. With high resolution methods, which made it possible to separate 1H NMR spectrum of (PVA-SeO2-SiC) (90Atom) structure, interactions were characterized by 1H NMR chemical shifts of SeO2. The results indicated to the PVA-SeO2-SiC (90Atom) structures have good optical and electronic properties with low energy band gap (2.648eV) which make it appropriate for many applications.

CONFLICT OF INTEREST
The authors declare that there is no conflict of interests regarding the publication of this manuscript.