A systematic investigation of structural properties and vertical excitation energies of a series of structurally modified 11-cis-retinal chromophores in vacuo was performed by means of multiconfigurational second-order perturbation theory (CASPT2). CASPT2-based geometries agree reasonably well with Møller-Plesset second-order perturbation theory (MP2), local second-order approximate coupled cluster singles and doubles (LCC2), and density functional theory (DFT) geometries, while the complete active space self-consistent field (CASSCF) method exaggerates dramatically the bond length pattern in the polyene chain. The quality of the resulting vertical excitation energies obtained by employing CASSCF, second-order approximate coupled cluster singles and doubles (CC2), LCC2, and time-dependent density functional theory (TD-DFT) approaches is assessed with respect to the CASPT2 data. We show that the commonly used CASSCF/CASPT2 approach works reasonably well in the case of vertical excitation energies of planar structures, but lack of dynamic correlation leads to large errors in energetics for strongly strained structures. For example, the highly twisted conformers of 9,10-dimethyl and 9,10,13-trimethyl species are found as global minima at the CASSCF level, whereas they turn almost planar at the CASPT2, MP2, LCC2, and DFT levels of theory. The CC2 method has shown a remarkable performance, manifested by a maximum deviation of 0.05 eV from the reference CASPT2 results, whereas the local version of CC2 seems to fail to describe the charge-transfer character of the S0 → S1 transitions correctly. We believe that our CASPT2 benchmark set will provide a reference that can be utilized for validation and development studies on 11-cis-retinal protonated Schiff base chromophore analogues.

The effect of the quality of the ground-state geometry on excitation energies in the retinal chromophore minimal model (PSB3) was systematically investigated using various single- (within Møller-Plesset and coupled-cluster frameworks) and multiconfigurational [within complete active space self-consistent field (CASSCF) and CASSCF-based perturbative approaches: second-order CASPT2 and third-order CASPT3] methods. Among investigated methods, only CASPT3 provides geometry in nearly perfect agreement with the CCSD(T)-based equilibrium structure. The second goal of the present study was to assess the performance of the CASPT2 methodology, which is popular in computational spectroscopy of retinals, in describing the excitation energies of low-lying excited states of PSB3 relative to CASPT3 results. The resulting CASPT2 excitation energy error is up to 0.16 eV for the S0 → S1 transition but only up to 0.06 eV for the S0 → S2 transition. Furthermore, CASPT3 excitation energies practically do not depend on modification of the zeroth-order Hamiltonian (so-called IPEA shift parameter), which does dramatically and nonsystematically affect CASPT2 excitation energies.

This study provides gas-phase S excited-state geometries along with emission and adiabatic energies for methylated/demethylated and ring-locked analogues of protonated Schiff base retinal models comprising system of five conjugated double bonds (PSB5), using second order multiconfiguration perturbation theory (CASPT2). CASPT2 results serve as reference data to assess the performance of CC2 (second-order approximate coupled cluster singles and doubles) and a commonly used CASSCF/CASPT2 protocol, that is, complete active space self-consistent field (CASSCF) geometry optimization followed by CASPT2 energy calculation. We find that the CASSCF methodology fails to locate planar S minimum energy structures for four out of five investigated planar models in contrast to CC2 and CASPT2 methods. However, for those which were found: one planar and two twisted minima, there is an excellent agreement between CASSCF and CASPT2 results in terms of geometrical parameters, one-electron properties, as well as emission and adiabatic energies. CC2 performs well for in-plane S minima and their spectroscopic and electronic properties. However, this picture deteriorates for twisted minima. As expected, the CC2 description of the S electronic state, with strong multireference and significant double excitation character, is very poor, exhibiting errors in transition energies exceeding 1 eV. They may be substantially diminished by recalculating transition energies with CASPT2 method. Our work shows that CASSCF/CASPT2 and CC2 shortcomings may influence gas-phase retinal analogues' excited state description in a dramatic way. © 2017 Wiley Periodicals, Inc.

Ab initio multiconfigurational quantum chemical methodology combined with molecular mechanics (CASPT2//CASSCF/AMBER) was applied to probe impacts of retinal protonated Schiff base (RPSB) polyene methylation and/or demethylation on the mechanism of photochemical isomerization in bovine rhodopsin. We have examined structural and spectroscopic properties of wild-type rhodopsin (with 11-cis-9,13-dimethyl-RPSB) and artificial rhodopsins, hosting four 11-cis-RPSB derivatives, 13-demethyl-, 9-demethyl-, 10-methyl-13-demethyl-, and 10-methyl-RPSB, evolving along the photoisomerization coordinate. It is found that the addition of 10-methyl or/and deletion of 9-/13-methyl groups do not appear to interfere structurally with the photoisomerization pathway in the S1 excited state. Remarkably, the two-mode space-saving mechanism initiated by bond order inversion and followed by asynchronous bicycle-pedal distortion in the RPSB backbone drives the photoreaction in all rhodopsin analogues studied here. However, methylation and/or demethylation is responsible for perturbation of excess energy deposited in the conical intersection structures. The analysis of photon energy stored by bathorhodopsin in synthetic pigments reveals that it is affected by steric crowding of methyl substituents in the RPSB backbone.

ABSTRAKTWstęp: Badanie jakości życia pacjentów chorujących na nowotwory jest przedmiotem ogromnej liczby prowadzonych badań z dziedziny psychoonkologii i psychologii zdrowia. Rzadziej podejmowana tematyka duchowości wydaje się ważną sferą życia pacjentów, która może warunkować stopień zadowolenia z życia (jakość życia). Ze względu na dużą popularność tematyki, ale małą liczbę doniesień w zakresie relacji obu aspektów życia osób dotkniętych chorobą nowotworową, w niniejszym badaniu podjęto próbę analizy związku tych zmiennych.Materiały i metody: Do badania zaproszono 94 osoby, z czego 44 w momencie badania chorowały na różne postaci nowotworu, a pozostałe 50 osób stanowiło grupę porównawczą (osoby zdrowe). Dokonano pomiaru zadowolenia z różnych aspektów życia, a także siły duchowości badanych osób, wykorzystując w tym celu metody kwestionariuszowe.Wyniki: Wykazano, że osoby chore gorzej oceniają zadowolenie ze swojego dotychczasowego życia, zadowolenie ze swojego zdrowia oraz ze sfery fizycznej. W badaniu sfery duchowości osoby chore uzyskały wyższe wyniki w skalach siły wiary oraz nasilenia postawy religijnej w porównaniu z osobami zdrowymi. Dowiedziono, że u osób zdrowych zadowolenie z życia jest uwarunkowane poczuciem harmonii życiowej i sensu życia. Natomiast u osób chorych związek zadowolenia z harmonią życiową jest silniejszy, a ponadto wyniki wskazały na znaczenie wrażliwości etycznej dla oceny własnego zadowolenia, czego nie zaobserwowano w grupie osób zdrowych.Wnioski: Mniejsze zadowolenie z życia prawdopodobnie wynika z bilansu zysków i strat dokonywanego przez chorych w obliczu ciężkiej choroby, a nawet ryzyka śmierci. Większe nasilenie wymiarów duchowości może wynikać z faktu, że osoby chorujące przewlekle lub nieuleczalnie powierzają swoje życie istocie wyższej, aby zyskać wiarę i nadzieję na dalszą walkę z chorobą. Zmianie ulega system wartości pacjenta – zadowolenie z życia, poza poczuciem harmonii życiowej, zaczyna być uwarunkowane wrażliwością etyczną chorego.