electronic effects were investigated on the singlet–triplet energy gaps of divalent unsaturated seven- membered ring r2c6h6m (m=c, si, ge, sn, pb, r= –h, -ch3, i-pr , t-bu) at b3lyp/6-311++g** level. all the triplet states of r2c6h6c were more stable than the related the singlet states while all the singlet states of r2c6h6m (m= si, ge, sn, pb, r= –h, -ch3, i-pr , t-bu) were more stable than th...

Electronic effects were investigated on the singlet–triplet energy gaps of divalent unsaturated seven- membered ring R2C6H6M (M=C, Si, Ge, Sn, Pb, R= –H, -CH3, i-Pr , t-Bu) at B3LYP/6-311++G** level. All the triplet states of R2C6H6C were more stable than the related the singlet states while all the singlet states of R2C6H6M (M= Si, Ge, Sn, Pb, R= –H, -CH3, i-Pr , t-Bu) were more stable than th...

Energy gaps, AXsar (X=E, H and G) (AX.,.,-=lia,„,,,InrX“dpka,) between single (s) and triplet (I) states werecalculated at B3LTP/6-3 I 1.HO" level of theory. Our results showed that electron donating substituents(G = -NHz, -OH. -CH), -F, -Cl and -Br) at phenyl group cause to increase and electron withdrawingsubstiluents (G -CF2. and -NO:) lead to decrease the singlet-triplet energy gaps of Ar -...

In recent work, thermal energy gaps. AE, it °PUPS gas, Ana; Gibbs free energy gaps, AG.,, between singlet(s) and triplet 0) states of 5.12C3H2C, I m (4 N. P. As and Sb) were calculated and compared with thoseanalogues. MC2113C, (M= CIL N. P. As and Sb) at B3LYIE6-311-NG" level of theory. Our itself showedthat Gibbs free energy gaps. AG, for l uu and 1 p are less than IS and I's, respectively. I...

The effects of halogens; fluorine, chlorine and bromine, on the stability and multiplicity of phenylcarbenes / silylenes/ germylenes structures are compared and contrasted at B3LYP/6-311++G**//B3LYP/6-31+G* level. The singlet-triplet energy gaps, ΔES-T , values for all the above speciesincrease through fluorinated up, ΔES-Ts and ΔEHOMO–LUMOs support the stability of the singlet statesinspite of...

the effects of halogens; fluorine, chlorine and bromine, on the stability and multiplicity of phenylcarbenes / silylenes/ germylenes structures are compared and contrasted at b3lyp/6-311++g**//b3lyp/6-31+g* level. the singlet-triplet energy gaps, δes-t , values for all the above speciesincrease through fluorinated up, δes-ts and δehomo–lumos support the stability of the singlet statesinspite of...

Trends in the singlet-triplet state-splittings of substituted carbenes are found to be reproduced accurately with a very simple level of ab initio theory. The minimum balanced description, GVB( 1 /2), with a simple basis set yields singlet-triplet gaps that correlate linearly with available accurate values. This linear relationship is exploited to predict the state-splitting for the remaining m...

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...

The intersystem crossing rate for the transition between the lowest excited singlet and triplet electronic states of uracil was studied by means of ab initio methods. The rate was evaluated using the time-dependent approach based on the correlation function and its two approximations: the second-order cumulant expansion and the short-time approximation. The normal modes of the singlet and tripl...

The biradicaloid character of the ground-state structures of N2P2 rings is studied by using the high-level ab initio multiconfigurational CASPT2/CASSCF method. In order to obtain accurate descriptors, we combine two criteria: 1) singlet-triplet energy gaps and 2) relative values of the occupation numbers for bonding and antibonding orbitals associated with the radical sites. The singlet-triplet...