in this research, a semi empirical approach has been suggested for calculating the activation energyof unimolecular thermal decomposition of vinyl ethers yielding saturated products. the calculationprocedure is based on the use of molecular mechanics (mm) methods. these methods which involvethe construction of the transition state for a molecule mainly consider the formation of a “hydrogenbridg...

Equivalences, partitions and (bi)simulations are usually tackled using concrete relations. There are only few treatments by abstract relation algebra or category theory. We give an approach based on the theory of semirings and quantales. This allows applying the results directly to structures such as path and tree algebras which is not as straightforward in the other approaches mentioned. Also,...

b a c k g r o u n d & aim: multi-state models can help better understand the process of chronic diseases such as cancers.  these models  are influenced  by assumptions  like individual  homogeneity.  this study aimed to investigate the effect of lack of individual homogeneity  assumption  in multi-state models. methods & materials: to investigate the effect of lack of individual homogeneity ass...

Ab initio calculations at HF/6-31G* level of theory for geometry optimization and MP2/6-31G*//HF/6-31G* for a single point total energy calculation are reported for the importantenergy-minimum conformations and transition-state geometries of 1, 3-diazacyclohepta-1, 2-diene (2) and 1, 3-diazacycloocta-1, 2-diene (3). The C2 symmetric twist-chair (2-TC)conformation of 2 is calculated to be 7.4 kJ...

using hartree-fock su-sheriffer-heeger (hf-ssh) model, we have studied the dependence of the energies of the ground (magnetic triplet state) and the first exited (nonmagnetic singlet state) states of the size-2 trigonal zigzag graphene nanoflake (size-2 nf) on the intensity of an external in plane static electric field at zero temperature. we identify a transition from the magnetic triplet stat...

ab initio calculation at hf/6-31g* level of theory for geometry optimization and mp2/6-31g*//hf/6-31g* for a single point total energy calculation are reported for the important energyminimumconformations and transition-state geometries of of cyclodeca-1,2,3-triene (1). the mostfavorable conformation of 1 is a unsymmetrical twist-chair (1-tc) structure. degenerateinterconversion of 1-tc with it...

A theoretical study of the kinetic and mechanism of intramoleccha cychcation of (1)-undeca-7,8-dien-2-yne was performed using MT methods at B3LYP and B3PW91 levels of theory using 6-311g, 6-311C.6-31 IGs*, 6-31I+G, 6-31 I4-SG and 6-3114H-Gs* basis seo. Equilibrium molecular geometries andharmonic vibrational frequencies of the reaccint, transition state and product wens calculated. Theconsidere...