Accurate calculation of the ionization energies of the chlorine lone pairs in 1,1,1-trifluoro-2-chloroethane (HCFC-133a)

Rodrigues, Gessenildo Pereira; Júnior, Juracy Regis de Lucena; Ventura, Elizete; Monte, Silmar A. do

doi:10.1007/s00894-014-2393-3

Cited by 4 publications

(9 citation statements)

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“…The energy differences between the A′ and A″ states arising from the same configuration (and involving excitation from the n orbitals) are in the range from 0.07 to 0.15 eV, and are compatible with the difference of 0.09 eV between the ionization potentials of the n 1 and n 2 lone pairs computed at the ROCCSD(T)/CBS level. 50 As can also be seen from Table 2, the ⟨r 2 ⟩ values lead to a clear separation between the valence (105 a 0 2 ) and Rydberg (132−159 a 0 2 ) states, although the ⟨r 2 ⟩ values for the nσ* states are significantly larger than that of the ground state (88 a 0…”

Section: Resultsmentioning

confidence: 63%

Photoinduced Formation of H-Bonded Ion Pair in HCFC-133a

et al. 2019

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High-level multireference electronic structure calculations have been performed to study the Cl − yield from photoexcited CF3CH2Cl (HCFC-133a). The analysis of this process tells that it relates to an electron transfer from the carbon to the Cl atom, forming a highly polar contact ion-pair complex, CF3HCH + •••Cl − , in the excited (S3) state. This complex has a strong binding energy of 3.53 eV, from which 0.47 eV is due to an underlying hydrogen bond. Through comparison with the results obtained for the prototype CH3Cl system, where a similar ion-pair state associated with Cl − formation has also been observed, it is suggested that photodissociation of HCFC-133a can also yield Cl − through analogous process. This hypothesis is further supported by nonadiabatic dynamics simulations, which shows formation of the ion-pair complex in the subpicosecond time scale.

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Section: Resultsmentioning

confidence: 63%

Photoinduced Formation of H-Bonded Ion Pair in HCFC-133a

et al. 2019

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“…44 It is important to mention that the accuracy of such predictions depends on the absence of Rydberg-valence mixing. 16 As these orbitals (and the associated congurations) can affect the highest lying (3 1 A 1 , 4 1 A 1 , and 5 1 E or 3 3 A 1 and 5 3 E in the case of triplet states) states here studied and as they have not been included in the calculations, due to the prohibitively high computational effort involved, a lower accuracy is expected for these highest lying states, as compared to the lower lying ones. However, to the best of our knowledge there are no other highly correlated theoretical results concerning excited states of CH 3 Cl above $9.5 eV.…”

Section: ) Moleculementioning

confidence: 99%

“…In many cases the energies of Rydberg states can be estimated through the Rydberg formula: [15][16][17] DE ¼ IE À Z/2(n À d l ) 2 (1) quantum number l. As can be seen from this equation the energies of Rydberg states for each series (e.g. s, p, d,.)…”

Section: Introductionmentioning

confidence: 99%

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Valence and Rydberg states of CH₃Cl: a MR-CISD study

2014

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In this work ten singlet and nine triplet states are studied through multi-reference configuration interactions with singles and doubles (MR-CISD), including Davidson extensivity correction (MR-CISD+Q). For the first time the excited states whose energies are larger than $9.5 eV have been calculated using highly correlated methods. The energies, spatial extent (hr 2 i), configurations weights and oscillator strengths (f) have been computed. At the MR-CISD+Q level the excited states energies vary from $7.51 to 11.98 eV. The lowest (ns*) excited singlet state is significantly mixed with the n3p a1 and n3s Rydberg states, while the next (n3s) has a non-negligible mixture with the ns* state. The next three singlet states obtained result from the (n Cl ) 3 (3p e ) 1 configuration and are almost degenerate. The next (n3p a1 ) singlet state is significantly mixed with the ns* state, while the last three have s C-Cl / Rydberg (3s or 3p) as the main configurations. According to the f values the most intense transition is to the 4 1 A 1 state, a s3p a1 Rydberg state mixed with the ss* and s3s configurations. Our results indicate that the ss* configuration is responsible for the high f value of the gs / 4 1 A 1 transition. The Rydberg-valence mixing is greatly reduced in the triplet states whose singlet counterparts have significant multiconfigurational character.The 2 3 A 1 state (ss*) does not have its singlet counterpart, while the 4 1 A 1 state (s3p a1 + ss* + s3s) does not have its triplet counterpart. The obtained results are in good agreement with experimental results and with previous CASPT2 results.

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“…This omission may impact the evaluation of computational methods and properties by introducing a negative bias against halogen compounds. We particularly felt that in recent simulations of halo-compounds of atmospheric interest [30][31][32][33][34] , where we could not count on performance evaluation for any of the molecules of interest. Our aim in this study is to start to fill this knowledge gap, first, by proposing a clear set of molecules to be tested; and second, by evaluating them using few popular methods.…”

Section: Introductionmentioning

confidence: 99%

UV excitations of halons

Stojanović

Al‐Youbi

Aziz

et al. 2016

The Journal of Chemical Physics

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In the present study, we examined the UV excitations of a newly introduced molecular set, Halons-9, composed of nine gaseous halon molecules. The performance of the density functional-based multi-reference configuration interaction method (DFT/MRCI) and time-dependent density functional theory with CAM-B3LYP functional (TD-CAM-B3LYP) in the computation of singlet and triplet excited states of this set was evaluated against coupled-cluster with singles and doubles (CCSD). Excited states up to the corresponding ionization limits, including both localized and delocalized excitations, have been benchmarked. TD-CAM-B3LYP significantly underestimates excitation energies of the higher mixed valence-Rydberg and Rydberg states, with computed mean absolute deviations from the equation of motion (EOM)-CCSD results 1.06 and 0.76 eV, respectively. DFT/MRCI gives a significantly better description of higher excited states, albeit still poor, compared to the TD-CAM-B3LYP. The mean absolute deviations of mixed valence-Rydberg and Rydberg states from the reference EOM-CCSD values are 0.66 and 0.47 eV, respectively. The performance of DFT/MRCI for description of strongly correlated states with valence-Rydberg mixing is still not satisfactory enough. On the other hand, oscillator strengths of most of singlet states obtained with both methods are close to the EOM-CCSD values. The largest deviations, occurring in the case of several high-lying multiconfigurational states, are of an order of magnitude.

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Accurate calculation of the ionization energies of the chlorine lone pairs in 1,1,1-trifluoro-2-chloroethane (HCFC-133a)

Cited by 4 publications

References 53 publications

Photoinduced Formation of H-Bonded Ion Pair in HCFC-133a

Photoinduced Formation of H-Bonded Ion Pair in HCFC-133a

Valence and Rydberg states of CH₃Cl: a MR-CISD study

UV excitations of halons

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Accurate calculation of the ionization energies of the chlorine lone pairs in 1,1,1-trifluoro-2-chloroethane (HCFC-133a)

Cited by 4 publications

References 53 publications

Photoinduced Formation of H-Bonded Ion Pair in HCFC-133a

Photoinduced Formation of H-Bonded Ion Pair in HCFC-133a

Valence and Rydberg states of CH3Cl: a MR-CISD study

UV excitations of halons

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Valence and Rydberg states of CH₃Cl: a MR-CISD study