Hybrid methods combining different levels of electronic structure quantum mechanical computations with vibrational perturbation theory have been increasingly used in anharmonic simulations of vibrational spectra to achieve accurate results with containable computational costs. However, energy has often been the main focus of these studies, so precision in predicting intensities was systematically overlooked. This situation is largely due to two aspects stemming from theory and experiment. Theoretically, implementations are fewer, and intensity-specific resonance analysis methods were not available until very recently and are still lacking extensive testing. Experimentally, high-resolution vibrational spectra of suitable molecular systems, which could really show the effects of different hybrid schemes on the vibrational intensities, remain scarce. A good candidate in this regard is uracil. Having been extensively studied experimentally, its IR spectrum is well-known over a wide range and at high definition. The patterns displayed by the band shapes represent an excellent challenge to validate and tune our recently developed automated tool to identify intensity-specific resonances. In this work, we compare the newly simulated spectra with state-of-the-art experimental data and propose an extensive analysis over a wide range covering 300 to 6200 cm-1, including 3-quanta transitions. These will provide valuable guides and references for further measurements in the mid-infrared (MIR) and near-infrared (NIR) regions, which have not been reported until now. The methods and protocols applied in this article can also be used for other molecules with complex resonance patterns.

Classe di Scienze Scuola Normale Superiore Piazza dei Cavalieri 7 56126 Pisa Italy

Department of Physics College of Sciences Shanghai University 99 Shangda Road Shanghai 200444 China

Faculty of Chemistry University of Wroclaw F Joliot Curie 14 50 383 Wroclaw Poland

Institute of Organic Chemistry and Biochemistry Czech Academy of Science Flemingovo náměstí 2 16610 Prague Czech Republic

See more in PubMed

Barone V., Alessandrini S., Biczysko M., Cheeseman J. R., Clary D. C., McCoy A. B., DiRisio R. J., Neese F., Melosso M., Puzzarini C.. Computational molecular spectroscopy. Nat. Rev. Methods Primers. 2021;1:38. doi: 10.1038/s43586-021-00034-1. DOI

Puzzarini C., Bloino J., Tasinato N., Barone V.. Accuracy and Interpretability: The Devil and the Holy Grail. New Routes across Old Boundaries in Computational Spectroscopy. Chem. Rev. 2019;119:8131–8191. doi: 10.1021/acs.chemrev.9b00007. PubMed DOI

Tennyson J.. Perspective: Accurate ro-vibrational calculations on small molecules. J. Chem. Phys. 2016;145:120901. doi: 10.1063/1.4962907. PubMed DOI

Mellor T. M., Owens A., Tennyson J., Yurchenko S. N.. MARVEL analysis of high-resolution spectra of thioformaldehyde (H2CS) J. Mol. Spectrosc. 2023;391:111732. doi: 10.1016/j.jms.2022.111732. DOI

Tóbiás R., Furtenbacher T., Tennyson J., Császár A. G.. Accurate empirical rovibrational energies and transitions of H2 16O. Phys. Chem. Chem. Phys. 2019;21:3473–3495. doi: 10.1039/C8CP05169K. PubMed DOI

Al-Derzi A. R., Tennyson J., Yurchenko S. N., Melosso M., Jiang N., Puzzarini C., Dore L., Furtenbacher T., Tóbiás R., Császár A. G.. An improved rovibrational linelist of formaldehyde, H2 12 C 16O. Journal of Quantitative Spectroscopy and Radiative Transfer. 2021;266:107563. doi: 10.1016/j.jqsrt.2021.107563. DOI

Barone V., Biczysko M., Bloino J.. Fully anharmonic IR and Raman spectra of medium-size molecular systems: accuracy and interpretation. Phys. Chem. Chem. Phys. 2014;16:1759–1787. doi: 10.1039/C3CP53413H. PubMed DOI PMC

Abbate S., Castiglioni E., Gangemi F., Gangemi R., Longhi G.. NIR-VCD, vibrational circular dichroism in the near-infrared: Experiments, theory and calculations. Chirality. 2009;21:E242–E252. doi: 10.1002/chir.20805. PubMed DOI

Bloino J., Jähnigen S., Merten C.. After 50 Years of Vibrational Circular Dichroism Spectroscopy: Challenges and Opportunities of Increasingly Accurate and Complex Experiments and Computations. J. Phys. Chem. Lett. 2024;15:8813–8828. doi: 10.1021/acs.jpclett.4c01700. PubMed DOI

Bloino J., Biczysko M., Barone V.. Anharmonic Effects on Vibrational Spectra Intensities: Infrared, Raman, Vibrational Circular Dichroism, and Raman Optical Activity. J. Phys. Chem. A. 2015;119:11862–11874. doi: 10.1021/acs.jpca.5b10067. PubMed DOI PMC

Crawford T. D.. Ab initio calculation of molecular chiroptical properties. Theor. Chem. Acc. 2006;115:227–245. doi: 10.1007/s00214-005-0001-4. DOI

Helgaker T., Coriani S., Jo̷rgensen P., Kristensen K., Olsen J., Ruud K.. Recent Advances in Wave Function-Based Methods of Molecular-Property Calculations. Chem. Rev. 2012;112:543–631. doi: 10.1021/cr2002239. PubMed DOI

Yuan X., Halbert L., Pototschnig J. V., Papadopoulos A., Coriani S., Visscher L., Pereira Gomes A. S.. Formulation and Implementation of Frequency-Dependent Linear Response Properties with Relativistic Coupled Cluster Theory for GPU-Accelerated Computer Architectures. J. Chem. Theory Comput. 2024;20:677–694. doi: 10.1021/acs.jctc.3c00812. PubMed DOI

Norman P.. A perspective on nonresonant and resonant electronic response theory for time-dependent molecular properties. Phys. Chem. Chem. Phys. 2011;13:20519–20535. doi: 10.1039/c1cp21951k. PubMed DOI

Coriani S., Thorvaldsen A. J., Kristensen K., Jo̷rgensen P.. Variational response-function formulation of vibrational circular dichroism. Phys. Chem. Chem. Phys. 2011;13:4224–4229. doi: 10.1039/c0cp02230f. PubMed DOI

Crawford T. D., Kumar A., Bazanté A. P., Di Remigio R.. Reduced-scaling coupled cluster response theory: Challenges and opportunities. WIREs Comput. Mol. Sci. 2019;9:e1406. doi: 10.1002/wcms.1406. DOI

Shumberger B. M., Crawford T. D.. Simulation of Vibrational Circular Dichroism Spectra Using Second-Order Mo̷ller–Plesset Perturbation Theory and Configuration Interaction Doubles. J. Chem. Theory Comput. 2024;20:7254–7263. doi: 10.1021/acs.jctc.4c00747. PubMed DOI PMC

Beć K. B., Grabska J., Ozaki Y., Hawranek J. P., Huck C. W.. Influence of Non-fundamental Modes on Mid-infrared Spectra: Anharmonic DFT Study of Aliphatic Ethers. J. Phys. Chem. A. 2017;121:1412–1424. doi: 10.1021/acs.jpca.6b11734. PubMed DOI

Yang Q., Bloino J.. An Effective and Automated Processing of Resonances in Vibrational Perturbation Theory Applied to Spectroscopy. J. Phys. Chem. A. 2022;126:9276–9302. doi: 10.1021/acs.jpca.2c06460. PubMed DOI PMC

Nielsen H. H.. The Vibration-Rotation Energies of Molecules. Rev. Mod. Phys. 1951;23:90–136. doi: 10.1103/RevModPhys.23.90. DOI

Bowman J. M.. The self-consistent-field approach to polyatomic vibrations. Acc. Chem. Res. 1986;19:202–208. doi: 10.1021/ar00127a002. DOI

Császár A. G., Fábri C., Szidarovszky T., Mátyus E., Furtenbacher T., Czakó G.. The fourth age of quantum chemistry: molecules in motion. Phys. Chem. Chem. Phys. 2012;14:1085–1106. doi: 10.1039/C1CP21830A. PubMed DOI

Noga J., Bartlett R. J.. The full CCSDT model for molecular electronic structure. J. Chem. Phys. 1987;86:7041–7050. doi: 10.1063/1.452353. DOI

Watts J. D., Bartlett R. J.. The coupled-cluster single, double, and triple excitation model for open-shell single reference functions. J. Chem. Phys. 1990;93:6104–6105. doi: 10.1063/1.459002. DOI

Raghavachari K., Trucks G. W., Pople J. A., Head-Gordon M.. A fifth-order perturbation comparison of electron correlation theories. Chem. Phys. Lett. 1989;157:479–483. doi: 10.1016/S0009-2614(89)87395-6. DOI

Spiegel M., Semidalas E., Martin J. M. L., Bentley M. R., Stanton J. F.. Post-CCSD­(T) corrections to bond distances and vibrational frequencies: the power of Λ. Mol. Phys. 2023;122:e2252114. doi: 10.1080/00268976.2023.2252114. DOI

Heckert M., Kallay M., Tew D. P., Klopper W., Gauss J.. Basis-set extrapolation techniques for the accurate calculation of molecular equilibrium geometries using coupled-cluster theory. J. Chem. Phys. 2006;125:44108. doi: 10.1063/1.2217732. PubMed DOI

Heckert M., Kallay M., Gauss J.. Molecular equilibrium geometries based on coupled-cluster calculations including quadruple excitations. Mol. Phys. 2005;103:2109–2115. doi: 10.1080/00268970500083416. DOI

Watrous A. G., Westbrook B. R., Fortenberry R. C.. F12-TZ-cCR: A Methodology for Faster and Still Highly Accurate Quartic Force Fields. J. Phys. Chem. A. 2021;125:10532–10540. doi: 10.1021/acs.jpca.1c08355. PubMed DOI

Di Grande S., Kállay M., Barone V.. Accurate thermochemistry at affordable cost by means of an improved version of the JunChS-F12 model chemistry. J. Comput. Chem. 2023;44:2149–2157. doi: 10.1002/jcc.27187. PubMed DOI

Puzzarini C., Barone V.. Extending the molecular size in accurate quantum-chemical calculations: the equilibrium structure and spectroscopic properties of uracil. Phys. Chem. Chem. Phys. 2011;13:7189–7197. doi: 10.1039/c0cp02636k. PubMed DOI

Alessandrini S., Barone V., Puzzarini C.. Extension of the “Cheap” Composite Approach to Noncovalent Interactions: The jun-ChS Scheme. J. Chem. Theory Comput. 2020;16:988–1006. doi: 10.1021/acs.jctc.9b01037. PubMed DOI

Puzzarini C., Biczysko M., Barone V.. Accurate Anharmonic Vibrational Frequencies for Uracil: The Performance of Composite Schemes and Hybrid CC/DFT Model. J. Chem. Theory Comput. 2011;7:3702–3710. doi: 10.1021/ct200552m. PubMed DOI

Karton A., de Oliveira M. T.. Good Practices in Database Generation for Benchmarking Density Functional Theory. WIREs Comput. Mol. Sci. 2025;15:e1737. doi: 10.1002/wcms.1737. DOI

Biczysko M., Panek P., Scalmani G., Bloino J., Barone V.. Harmonic and Anharmonic Vibrational Frequency Calculations with the Double-Hybrid B2PLYP Method: Analytic Second Derivatives and Benchmark Studies. J. Chem. Theory Comput. 2010;6:2115–2125. doi: 10.1021/ct100212p. PubMed DOI

Puzzarini C., Biczysko M., Barone V.. Accurate Harmonic/Anharmonic Vibrational Frequencies for Open-Shell Systems: Performances of the B3LYP/N07D Model for Semirigid Free Radicals Benchmarked by CCSD­(T) Computations. J. Chem. Theory Comput. 2010;6:828–838. doi: 10.1021/ct900594h. PubMed DOI

Ravichandran L., Banik S.. Performance of different density functionals for the calculation of vibrational frequencies with vibrational coupled cluster method in bosonic representation. Theor. Chem. Acc. 2017;137:1. doi: 10.1007/s00214-017-2177-9. DOI

Mitra H., Roy T. K.. Comprehensive Benchmark Results for the Accuracy of Basis Sets for Anharmonic Molecular Vibrations. J. Phys. Chem. A. 2020;124:9203–9221. doi: 10.1021/acs.jpca.0c06634. PubMed DOI

Barone V., Ceselin G., Fusè M., Tasinato N.. Accuracy Meets Interpretability for Computational Spectroscopy by Means of Hybrid and Double-Hybrid Functionals. Front. Chem. 2020;8:584203. doi: 10.3389/fchem.2020.584203. PubMed DOI PMC

Yang Q., Mendolicchio M., Barone V., Bloino J.. Accuracy and Reliability in the Simulation of Vibrational Spectra: A Comprehensive Benchmark of Energies and Intensities Issuing From Generalized Vibrational Perturbation Theory to Second Order (GVPT2) Frontiers in Astronomy and Space Sciences. 2021;8:665232. doi: 10.3389/fspas.2021.665232. DOI

Biczysko M., Bloino J., Puzzarini C.. Computational challenges in Astrochemistry. WIREs Comput. Mol. Sci. 2018;8:e1349. doi: 10.1002/wcms.1349. DOI

Xu R., Jiang Z., Yang Q., Bloino J., Biczysko M.. Harmonic and anharmonic vibrational computations for biomolecular building blocks: Benchmarking DFT and basis sets by theoretical and experimental IR spectrum of glycine conformers. J. Comput. Chem. 2024;45:1846–1869. doi: 10.1002/jcc.27377. PubMed DOI

Schröder B., Rauhut G.. From the Automated Calculation of Potential Energy Surfaces to Accurate Infrared Spectra. J. Phys. Chem. Lett. 2024;15:3159–3169. doi: 10.1021/acs.jpclett.4c00186. PubMed DOI PMC

Fornaro T., Carnimeo I., Biczysko M.. Toward Feasible and Comprehensive Computational Protocol for Simulation of the Spectroscopic Properties of Large Molecular Systems: The Anharmonic Infrared Spectrum of Uracil in the Solid State by the Reduced Dimensionality/Hybrid VPT2 Approach. J. Phys. Chem. A. 2015;119:5313–5326. doi: 10.1021/jp510101y. PubMed DOI

Begue D., Carbonniere P., Pouchan C.. Calculations of Vibrational Energy Levels by Using a Hybrid ab Initio and DFT Quartic Force Field: Application to Acetonitrile. J. Phys. Chem. A. 2005;109:4611–4616. doi: 10.1021/jp0406114. PubMed DOI

Barone V., Biczysko M., Bloino J., Puzzarini C.. Characterization of the Elusive Conformers of Glycine from State-of-the-Art Structural, Thermodynamic, and Spectroscopic Computations: Theory Complements Experiment. J. Chem. Theory Comput. 2013;9:1533–1547. doi: 10.1021/ct3010672. PubMed DOI

Barone V., Biczysko M., Bloino J., Cimino P., Penocchio E., Puzzarini C.. CC/DFT Route toward Accurate Structures and Spectroscopic Features for Observed and Elusive Conformers of Flexible Molecules: Pyruvic Acid as a Case Study. J. Chem. Theory Comput. 2015;11:4342–4363. doi: 10.1021/acs.jctc.5b00580. PubMed DOI PMC

Sheng M., Silvestrini F., Biczysko M., Puzzarini C.. Structural and Vibrational Properties of Amino Acids from Composite Schemes and Double-Hybrid DFT: Hydrogen Bonding in Serine as a Test Case. J. Phys. Chem. A. 2021;125:9099–9114. doi: 10.1021/acs.jpca.1c06993. PubMed DOI

Barone V.. Vibrational zero-point energies and thermodynamic functions beyond the harmonic approximation. J. Chem. Phys. 2004;120:3059–3065. doi: 10.1063/1.1637580. PubMed DOI

Barone V.. Anharmonic vibrational properties by a fully automated second-order perturbative approach. J. Chem. Phys. 2005;122:014108. doi: 10.1063/1.1824881. PubMed DOI

Vázquez J., Stanton J. F.. Simple­(r) algebraic equation for transition moments of fundamental transitions in vibrational second-order perturbation theory. Mol. Phys. 2006;104:377–388. doi: 10.1080/00268970500290367. DOI

Barone V., Bloino J., Guido C. A., Lipparini F.. A fully automated implementation of VPT2 Infrared intensities. Chem. Phys. Lett. 2010;496:157–161. doi: 10.1016/j.cplett.2010.07.012. DOI

Bloino J., Barone V.. A second-order perturbation theory route to vibrational averages and transition properties of molecules: General formulation and application to infrared and vibrational circular dichroism spectroscopies. J. Chem. Phys. 2012;136:124108. doi: 10.1063/1.3695210. PubMed DOI

Krasnoshchekov S. V., Dobrolyubov E. O., Chang X.. Hypofluorous acid (HOF): A molecule with a rare (1,-2,-1) vibrational resonance and (8,3,2) polyad structure revealed by Padé-Hermite resummation of divergent Rayleigh-Schrödinger perturbation theory series. Journal of Quantitative Spectroscopy and Radiative Transfer. 2021;268:107620. doi: 10.1016/j.jqsrt.2021.107620. DOI

Franke P. R., Stanton J. F., Douberly G. E.. How to VPT2: Accurate and Intuitive Simulations of CH Stretching Infrared Spectra Using VPT2+K with Large Effective Hamiltonian Resonance Treatments. J. Phys. Chem. A. 2021;125:1301–1324. doi: 10.1021/acs.jpca.0c09526. PubMed DOI

Martin J. M. L., Lee T. J., Taylor P. R., François J.. The anharmonic force field of ethylene, C2H4, by means of accurate ab initio calculations. J. Chem. Phys. 1995;103:2589–2602. doi: 10.1063/1.469681. DOI

Krasnoshchekov S. V., Isayeva E. V., Stepanov N. F.. Criteria for first- and second-order vibrational resonances and correct evaluation of the Darling-Dennison resonance coefficients using the canonical Van Vleck perturbation theory. J. Chem. Phys. 2014;141:234114. doi: 10.1063/1.4903927. PubMed DOI

Krasnoshchekov S. V., Dobrolyubov E. O., Syzgantseva M. A., Palvelev R. V.. Rigorous vibrational Fermi resonance criterion revealed: two different approaches yield the same result. Mol. Phys. 2020;118:e1743887. doi: 10.1080/00268976.2020.1743887. DOI

Bloino J., Baiardi A., Biczysko M.. Aiming at an accurate prediction of vibrational and electronic spectra for medium-to-large molecules: An overview. Int. J. Quantum Chem. 2016;116:1543–1574. doi: 10.1002/qua.25188. DOI

Estrin D. A., Paglieri L., Corongiu G.. A Density Functional Study of Tautomerism of Uracil and Cytosine. J. Phys. Chem. 1994;98:5653–5660. doi: 10.1021/j100073a014. DOI

Tian S., Zhang C., Zhang Z., Chen X., Xu K.. How many uracil tautomers there are? Density functional studies of stability ordering of tautomers. Chem. Phys. 1999;242:217–225. doi: 10.1016/S0301-0104(99)00009-9. DOI

Barnes A., Stuckey M., Le Gall L.. Nucleic acid bases studied by matrix isolation vibrational spectroscopy: Uracil and deuterated uracils. Spectrochimica Acta Part A: Molecular Spectroscopy. 1984;40:419–431. doi: 10.1016/0584-8539(84)80073-2. DOI

Ivanov A., Plokhotnichenko A. M., Radchenko E. D., Sheina G. G., Blagoi Y. P.. FTIR spectroscopy of uracil derivatives isolated in Kr, Ar and Ne matrices: matrix effect and Fermi resonance. J. Mol. Struct. 1995;372:91–100. doi: 10.1016/S0166-1280(05)80001-6. DOI

Krasnoshchekov S. V., Vogt N., Stepanov N. F.. Ab Initio Anharmonic Analysis of Vibrational Spectra of Uracil Using the Numerical-Analytic Implementation of Operator Van Vleck Perturbation Theory. J. Phys. Chem. A. 2015;119:6723–6737. doi: 10.1021/acs.jpca.5b03241. PubMed DOI

Fornaro T., Burini D., Biczysko M., Barone V.. Hydrogen-Bonding Effects on Infrared Spectra from Anharmonic Computations: Uracil–Water Complexes and Uracil Dimers. J. Phys. Chem. A. 2015;119:4224–4236. doi: 10.1021/acs.jpca.5b01561. PubMed DOI

Vogt N., Khaikin L. S., Grikina O. E., Rykov A. N.. A benchmark study of molecular structure by experimental and theoretical methods: Equilibrium structure of uracil from gas-phase electron diffraction data and coupled-cluster calculations. J. Mol. Struct. 2013;1050:114–121. doi: 10.1016/j.molstruc.2013.07.014. DOI

Colarusso P., Zhang K., Guo B., Bernath P. F.. The infrared spectra of uracil, thymine, and adenine in the gas phase. Chem. Phys. Lett. 1997;269:39–48. doi: 10.1016/S0009-2614(97)00245-5. DOI

Lord R., Thomas G.. Raman spectral studies of nucleic acids and related moleculesI Ribonucleic acid derivatives. Spectrochimica Acta Part A: Molecular Spectroscopy. 1967;23:2551–2591. doi: 10.1016/0584-8539(67)80149-1. DOI

Aamouche A., Ghomi M., Coulombeau C., Jobic H., Grajcar L., Baron M. H., Baumruk V., Turpin P. Y., Henriet C., Berthier G.. Neutron Inelastic Scattering, Optical Spectroscopies and Scaled Quantum Mechanical Force Fields for Analyzing the Vibrational Dynamics of Pyrimidine Nucleic Acid Bases. 1. Uracil. The Journal of Physical Chemistry. 1996;100:5224–5234. doi: 10.1021/jp952485x. DOI

Susi H., Ard J.. Vibrational spectra of nucleic acid constituentsI: Planar vibrations of uracil. Spectrochimica Acta Part A: Molecular Spectroscopy. 1971;27:1549–1562. doi: 10.1016/0584-8539(71)80211-8. DOI

Florián J., Hrouda V.. Scaled quantum mechanical force fields and vibrational spectra of solid state nucleic acid constituents V: thymine and uracil. Spectrochimica Acta Part A: Molecular Spectroscopy. 1993;49:921–938. doi: 10.1016/0584-8539(93)80211-R. DOI

Wojcik M. J.. Medium-frequency Raman spectra of crystalline uracil, thymine and their 1-methyl derivatives. J. Mol. Struct. 1990;219:305–310. doi: 10.1016/0022-2860(90)80073-S. DOI

Wójcik M., Rostkowska H., Szczepaniak K., Persont W.. Vibrational resonances in infrared spectra of uracils. Spectrochimica Acta Part A: Molecular Spectroscopy. 1989;45:499–502. doi: 10.1016/0584-8539(89)80047-9. DOI

Nowak M. J.. IR matrix isolation studies of nucleic acid constituents: the spectrum of monomeric thymine. J. Mol. Struct. 1989;193:35–49. doi: 10.1016/0022-2860(89)80119-X. DOI

Graindourze M., Smets J., Zeegers-Huyskens T., Maes G.. Fourier transforminfrared spectroscopic study of uracil derivatives and their hydrogen bonded complexes with proton donors: Part I. Monomer infrared absorptions of uracil and some methylated uracils in argon matrices. J. Mol. Struct. 1990;222:345–364. doi: 10.1016/0022-2860(90)85045-K. DOI

Graindourze M., Grootaers T., Smets J., Zeegers-Huyskens T., Maes G.. FT-IR spectroscopic study of uracil derivatives and their hydrogen bonded complexes with proton donors: Part III. Hydrogen bonding of uracils with H2O in argon matrices. J. Mol. Struct. 1991;243:37–60. doi: 10.1016/0022-2860(91)87025-D. DOI

Maltese M., Passerini S., Nunziante-Cesaro S., Dobos S., Harsànyi L.. Infrared levels of monomeric uracil in cryogenic matrices. J. Mol. Struct. 1984;116:49–65. doi: 10.1016/0022-2860(84)80183-0. DOI

Szczesniak M., Nowak M. J., Rostkowska H., Szczepaniak K., Person W. B., Shugar D.. Matrix isolation studies of nucleic acid constituents. 1. Infrared spectra of uracil monomers. J. Am. Chem. Soc. 1983;105:5969–5976. doi: 10.1021/ja00357a002. DOI

Chin S., Scott I., Szczepani K., Person W. B.. Matrix isolation studies of nucleic acid constituents. 2. Quantitative ab initio prediction of the infrared spectrum of in-plane modes of uracil. J. Am. Chem. Soc. 1984;106:3415–3422. doi: 10.1021/ja00324a006. DOI

Barone V., Festa G., Grandi A., Rega N., Sanna N.. Accurate vibrational spectra of large molecules by density functional computations beyond the harmonic approximation: the case of uracil and 2-thiouracil. Chem. Phys. Lett. 2004;388:279–283. doi: 10.1016/j.cplett.2004.03.024. DOI

Rasheed T., Ahmad S., Afzal S., Rahimullah K.. Anharmonic vibrational analysis of uracil by ab initio Hartree–Fock and density functional theory calculations. Journal of Molecular Structure: THEOCHEM. 2009;895:18–20. doi: 10.1016/j.theochem.2008.10.013. DOI

Ten G. N., NechaeV V. V., Krasnoshchekov S. V.. Interpretation of vibrational IR spectrum of uracil using anharmonic calculation of frequencies and intensities in second-order perturbation theory. Opt. Spectrosc. 2010;108:37–44. doi: 10.1134/S0030400X10010078. DOI

Fornaro T., Biczysko M., Monti S., Barone V.. Dispersion corrected DFT approaches for anharmonic vibrational frequency calculations: nucleobases and their dimers. Phys. Chem. Chem. Phys. 2014;16:10112–10128. doi: 10.1039/C3CP54724H. PubMed DOI PMC

Él’kin P. M., Érman M. A., Pulin O. V.. Analysis of vibrational spectra of methyl-substituted uracils in the anharmonic approximation. J. Appl. Spectrosc. 2006;73:485–491. doi: 10.1007/s10812-006-0106-0. DOI

Pouchan C., Thicoipe S., De La Pierre M.. DFT modelling of the infrared spectra for the isolated and the micro-hydrated forms of uracil. Theor. Chem. Acc. 2019;138:36. doi: 10.1007/s00214-019-2431-4. DOI

Thomas P. S., Carrington T. Jr., Agarwal J., Schaefer H. F. III. Using an iterative eigensolver and intertwined rank reduction to compute vibrational spectra of molecules with more than a dozen atoms: Uracil and naphthalene. J. Chem. Phys. 2018;149:064108. doi: 10.1063/1.5039147. PubMed DOI

Baiardi A., Kelemen A. K., Reiher M.. Excited-State DMRG Made Simple with FEAST. J. Chem. Theory Comput. 2022;18:415–430. doi: 10.1021/acs.jctc.1c00984. PubMed DOI

Santra G., Sylvetsky N., Martin J. M. L.. Minimally Empirical Double-Hybrid Functionals Trained against the GMTKN55 Database: revDSD-PBEP86-D4, revDOD-PBE-D4, and DOD-SCAN-D4. J. Phys. Chem. A. 2019;123:5129–5143. doi: 10.1021/acs.jpca.9b03157. PubMed DOI PMC

Becke A. D.. Density-functional exchange-energy approximation with correct asymptotic behavior. Phys. Rev. A. 1988;38:3098–3100. doi: 10.1103/PhysRevA.38.3098. PubMed DOI

Grimme S., Antony J., Ehrlich S., Krieg H.. A consistent and accurate ab initio parametrization of density functional dispersion correction (DFT-D) for the 94 elements H-Pu. J. Chem. Phys. 2010;132:154104. doi: 10.1063/1.3382344. PubMed DOI

Grimme S., Ehrlich S., Goerigk L.. Effect of the damping function in dispersion corrected density functional theory. J. Comput. Chem. 2011;32:1456–1465. doi: 10.1002/jcc.21759. PubMed DOI

Papajak E., Zheng J., Xu X., Leverentz H. R., Truhlar D. G.. Perspectives on Basis Sets Beautiful: Seasonal Plantings of Diffuse Basis Functions. J. Chem. Theory Comput. 2011;7:3027–3034. doi: 10.1021/ct200106a. PubMed DOI

Martin, J. ; Alsenoy, C. V. . GAR2PED; University of Antwerp, 1995.

Duschinsky F.. On the interpretation of electronic spectra of polyatomic molecules. I. Concerning the Franck-Condon principle. Acta Physicochim. URSS. 1937;7:551–566.

Rosnik A. M., Polik W. F.. VPT2+K spectroscopic constants and matrix elements of the transformed vibrational Hamiltonian of a polyatomic molecule with resonances using Van Vleck perturbation theory. Mol. Phys. 2014;112:261–300. doi: 10.1080/00268976.2013.808386. DOI

Kreienborg N. M., Yang Q., Pollok C. H., Bloino J., Merten C.. Matrix-isolation and cryosolution-VCD spectra of alpha-pinene as benchmark for anharmonic vibrational spectra calculations. Phys. Chem. Chem. Phys. 2023;25:3343–3353. doi: 10.1039/D2CP04782A. PubMed DOI

Császár A. G., Demaison J., Rudolph H. D.. Equilibrium Structures of Three-, Four-, Five-, Six-, and Seven-Membered Unsaturated N-Containing Heterocycles. J. Phys. Chem. A. 2015;119:1731–1746. doi: 10.1021/jp5084168. PubMed DOI

Brünken S., McCarthy M. C., Thaddeus P., Godfrey P. D., Brown R. D.. Improved line frequencies for the nucleic acid base uracil for a radioastronomical search. Astron. Astrophys. 2006;459:317. doi: 10.1051/0004-6361:20065777. DOI

Vaquero V., Sanz M. E., López J. C., Alonso J. L.. The structure of uracil: a laser ablation rotational study. J. Phys. Chem. Lett. 2007;111A:3443. doi: 10.1021/jp071642c. PubMed DOI

Yarasi S., Billinghurst B. E., Loppnow G. R.. Vibrational properties of thymine, uracil and their isotopomers. J. Raman Spectrosc. 2007;38:1117–1126. doi: 10.1002/jrs.1722. DOI

Leś A., Adamowicz L., Nowak M. J., Lapinski L.. The infrared spectra of matrix isolated uracil and thymine: An assignment based on new theoretical calculations. Spectrochimica Acta Part A: Molecular Spectroscopy. 1992;48:1385–1395. doi: 10.1016/0584-8539(92)80144-L. DOI

Choi M. Y., Miller R. E.. Infrared Laser Spectroscopy of Uracil and Thymine in Helium Nanodroplets: Vibrational Transition Moment Angle Study. J. Phys. Chem. A. 2007;111:2475–2479. doi: 10.1021/jp0674625. PubMed DOI

Aamouche A., Berthier G., Coulombeau C., Flament J., Ghomi M., Henriet C., Jobic H., Turpin P.. Molecular force fields of uracil and thymine, through neutron inelastic scattering experiments and scaled quantum mechanical calculations. Chem. Phys. 1996;204:353–363. doi: 10.1016/0301-0104(95)00298-7. DOI

Fujii M., Tamura T., Mikami N., Ito M.. Electronic spectra of uracil in a supersonic jet. Chem. Phys. Lett. 1986;126:583–587. doi: 10.1016/S0009-2614(86)80178-6. DOI