ab initio LCAO/LDA calculations which contains two-electron integrals has been undertaken to also calculate the electronic structure for the four different conformations of PMVC. The ab initio method involves a more fundamental approach to solving the Schrodinger equation than does the semiempirical method, although there are some assumptions implicit in such calculations (16), The basic approximation of ab initio calculation is that the total wave function is a single Slater determinant and the resultant expression of the molecular orbitals is a linear combination of atomic orbital basis functions (LCAO): in other word, ab initio calculation can be initiated once a basis for the LCAO is chosen.
A series of molecular orbitals, whose energy levels are with respect to the vacuum energy [E.sub.vac], were obtained by the calculations of these two methods (LCAO and PM3) on the short segments of PMVC chains.
While the Langmuir-Blodnett rown films of PMVC could adopt a geometric structure with all dipoles pointing to one direction and all the methyl groups sitting on one side of molecule, as shown schematically in Fig.
The alternating trans-gauche conformation is also possible for the polymer structure in ordered Langmuir-Blodgett films of PMVC just as is the case for P(VDF-TrFE) in the paraelectric phase (3), (4).
This agreement between the experimental electronic structure and the calculated model DOSs suggests (hat Langmuir-BJodgett PMVC films adopt the all-trans conformation with all dipoles aligned.
In spite of the differences, both the ab initio methods and the semiempirical PM3 calculations suggest that the all-trans conformation is the only structural phase of PMVC films at room temperature and below.
the high incidences of interpersonal violence (IPV) and pedestrian-motor vehicle collisions (PMVCs).
Breakdown of all cases of major trauma showed the following: IPV 2 594 patients (69.4%), with penetrating trauma secondary to stabbing in 911 (24.3%), isolated head injury in 632 (16.9%), penetrating trauma secondary to gunshot wounds (GSWs) in 542 (14.5%), crush injury secondary to community assault in 340 (9.1%), blunt force trauma secondary to assault in 170 (4.5%), blunt force trauma secondary to motor vehicle collisions (MVCs) in 650 (17.4%), blunt force trauma secondary to PMVCs in 285 (7.6%), and burns in 205 (5.4%).
They demonstrated a high burden of trauma as a result of RTCs, with PMVCs accounting for 41%.
Studies are needed to identify factors that increase or decrease the risk of RTCs, particularly PMVCs, in order to successfully implement effective interventions and legislation.
It further highlights the burden of PMVCs as a proportion of all RTCs.