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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Vibrational spectra of α-glucose, β-glucose, and Sucrose: Anharmonic calculations and experiment
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Vibrational spectra of α-glucose, β-glucose, and Sucrose: Anharmonic calculations and experiment

机译：α-葡萄糖，β-葡萄糖和蔗糖的振动光谱：非谐计算和实验

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摘要

The anharmonic vibrational spectra of R-D-glucose, β-D-glucose, and sucrose are computed by the vibrational self-consistent field (VSCF) method, using potential energy surfaces from electronic structure theory, for the lowest energy conformers that correspond to the gas phase and to the crystalline phase, respectively. The results are compared with ultraviolet-infrared (UV-IR) spectra of phenyl β-Dglucopyranoside in a molecular beam, with literature results for sugars in matrices and with new experimental data for the crystalline state. Car-Parrinello dynamics simulations are also used to study temperature effects on the spectra of R-D-glucose and β-D-glucose and to predict their vibrational spectra at 50, 150, and 300 K. The effects of temperature on the spectral features are analyzed and compared with results of the VSCF calculations conducted at 0 K. The main results include: (i) new potential surfaces, constructed from Hartree-Fock, adjusted to fit harmonic frequencies from Moller-Plesset (MP2) calculations, that give very good agreement with gas phase, matrix, and solid state spectra; (ii) computed infrared spectra of the crystalline solid of α-glucose, which are substantially improved by including mimic groups that represent the effect of the solid environment on the sugar; and (iii) identification of a small number of combination-mode transitions, which are predicted to be strong enough for experimental observation. The results are used to assess the role of anharmonic effects in the spectra of the sugars in isolation and in the solid state and to discuss the spectroscopic accuracy of potentials from different electronic structure methods.
机译：RD-葡萄糖，β-D-葡萄糖和蔗糖的非谐振动光谱通过振动自洽场（VSCF）方法，使用电子结构理论中的势能面，计算出与气体相对应的最低能构型相和结晶相。将结果与分子束中苯基β-D-吡喃葡萄糖苷的紫外-红外（UV-IR）光谱，基质中糖的文献结果以及晶体状态的新实验数据进行了比较。 Car-Parrinello动力学模拟还用于研究温度对RD-葡萄糖和β-D-葡萄糖光谱的影响，并预测它们在50、150和300 K时的振动光谱。分析了温度对光谱特征的影响并将其与在0 K下进行的VSCF计算结果进行比较。主要结果包括：（i）由Hartree-Fock构建的新势能面经过调整，以适应Moller-Plesset（MP2）计算的谐波频率，具有很好的一致性具有气相，基质和固态光谱; （ii）计算的α-葡萄糖晶体固体的红外光谱，通过包括代表固体环境对糖的影响的模拟基团而大大改善了该光谱; （iii）识别少量的组合模式过渡，预测这些过渡模式过渡足够强大以进行实验观察。该结果用于评估非谐效应在分离和固态糖的光谱中的作用，并讨论来自不同电子结构方法的电位的光谱准确性。

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