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The accurate measurement and calculation of molecular electron affinity has been a hot topic. The existing theoretical study does not consider the effects of different basic sets, or various correlation effects or zero point energy correction. In addition, there are some deviations of calculation results from experimental measurements. Therefore, we conduct a high-level ab initiostudy on the electron affinities of CO 2, OCS, CS 2and their corresponding anions
$ {\text{CO}}_{2}^{{ - }} $ , OCS –,$ {\text{CS}}_{2}^{{ - }} $ by adopting the coupled cluster with singles and doubles (triples) (CCSD(T)), spin-unrestricted open-shell coupled cluster with singles and doubles (triples) (UCCSD(T)), respectively. The equilibrium geometries of the ground states of these molecules are calculated under a series of extended correlation consistent basis sets aug-cc-pV ( X+ d)Z ( X= T, Q, 5) and complete basis set extrapolation (CBS) limit. The effects of core-valence (CV) electron correlation and scalar relativistic (SR) on equilibrium geometry of the ground state are studied, and our results are compared with previous experimental observations and theoretical data. Our calculations are in good agreement with the previous results. It is found that the calculations of equilibrium geometries of these molecules tend to converge. It is noted that the scalar relativistic effect has little influence on the equilibrium structure of the neutral molecule, but it has more significant influence on the bond angle of$ {\text{CS}}_{2}^{{ - }} $ .With the increase of atomic number, the core-valence correlation effect exerts a more remarkable influence on the equilibrium structures of ground states of CS 2and$ {\text{CS}}_{2}^{{ - }} $ molecules except for R C-Sof OCS –. Based on accurate structures, the adiabatic energy values of neutral molecules CO 2, OCS, CS 2by CCSD(T) method and those of$ {\text{CO}}_{2}^{{ - }} $ , OCS –,$ {\text{CS}}_{2}^{{ - }} $ by using UCCSD(T) and spin-restricted open-shell coupled cluster with singles and doubles (triples) (RCCSD(T)) are calculated, respectively. And finally, the adiabatic electron affinities (EAs) of the neutral molecules CO 2, OCS, CS 2are obtained. The effects of different basis sets, CBS, correlation effects and zero-point energy correction on the EA values of these molecules are investigated. It is found that both the scalar relativistic effect and the core-valence correlation effect affect the EAs of neutral molecules, and the core-valence correlation effect has a more significant effect on the EA value. The results show that the correlation effect has more significant influence on the adiabatic EA than the equilibrium structure of the ground state of neutral molecules. Based on the CBS+ΔCV+ΔDK+ΔZPE calculation, accurate EA information is acquired. Our results of EA values are within the experimental error. This work will enrich the information about spectral constants and electron affinities of carbon-containing triatomic molecules, and provide an important reference for experimental spectral analysis.-
Keywords:
- coupled cluster method/
- carbon-containing triatomic molecules/
- equilibrium geometry/
- electron affinities
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] -
AV(T+d)Z AV(Q+d)Z AV(5+d)Z CBS CO2 RC-O/Å 1.167 1.163 1.162 1.162 ${\text{CO}}_2^ - $ RC-O/Å 1.237 1.232 1.231 1.230 ∠OCO/(°) 137.6 137.7 137.8 137.9 OCS RC-O/Å 1.163 1.159 1.158 1.158 RC-S/Å 1.571 1.567 1.566 1.565 ${\mathrm{OCS}}^{ - } $ RC-O/Å 1.214 1.210 1.209 1.208 RC-S/Å 1.710 1.705 1.703 1.701 ∠OCS/(°) 136.5 136.4 136.5 136.5 CS2 RC-S/Å 1.562 1.558 1.557 1.555 $ {\text{CS}}_{2}^{{ - }} $ RC-S/Å 1.641 1.636 1.634 1.633 ∠SCS/(°) 143.3 143.5 143.6 143.7 
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本工作计算结果 其他计算结果 实验结果 CBS ΔCV ΔDK Total CO2 RC-O/Å 1.162 –0.002 0 1.160 1.143[19]/1.179[19]/1.1614[20]/1.164[20]/1.167[21] 1.162[13] $ {\text{CO}}_{2}^{{ - }} $ RC-O/Å 1.230 –0.002 0 1.228 1.225[19]/1.256[19]/1.230[20]/1.233[20]/1.237[21] 1.25[14] ∠OCO/(°) 137.9 0.1 0 138.0 135[19]/134.2[19]/137.9[20]/137.7[20]/136.7[21] 134[15] OCS RC-O/Å 1.158 –0.002 0 1.156 1.158[20]/1.161[20])/1.163[21] 1.156[16] RC-S/Å 1.565 –0.003 0 1.562 1.566[20]/1.563[20]/1.575[21] 1.561[16] ${\mathrm{OCS}}^{ - } $ RC-O/Å 1.208 –0.002 0 1.206 1.208[20]/1.209[20]/1.213[21] — RC-S/Å 1.701 –0.005 0 1.696 1.704[20]/1.707[20]/1.716[21] — ∠OCS/(°) 136.5 0.1 0 136.6 136.5[20]/136.3[20]/136.2[21] — CS2 RC-S/Å 1.555 –0.003 0 1.552 1.558[20]/1.557[20]/1.565[21] 1.556[17] $ {\text{CS}}_{2}^{{ - }} $ RC-S/Å 1.633 –0.004 0 1.629 1.635[20]/1.630[20]/1.646[21] — ∠SCS/(°) 143.7 0.2 –0.1 143.8 144[20]/145.2[20]/142.7[21] 141[18] DownLoad:
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绝热电子亲和能/eV UCCSD(T) RCCSD(T) AV(T+d)Z –0.631 –0.654 AV(Q+d)Z –0.630 –0.653 AV(5+d)Z –0.624 –0.648 Q5-CBS –0.616 –0.640 TQ5-CBS –0.619 –0.643 ΔCV –0.012 ΔDK –0.003 ΔZPE 0.090 Total –0.541a)/–0.544b) –0.565a)/–0.568b) Experiment –0.6 ± 0.2[4]/–0.44±0.2[5] Calculation –0.36[22]/–0.669[20]/–0.544[21] 注:a)Q5-CBS+ΔCV+ΔDK+ΔZPE result.
b)TQ5-CBS+ΔCV+ΔDK+ΔZPE result.DownLoad:
CSV
绝热电子亲和能/eV UCCSD(T) RCCSD(T) AV(T+d)Z 0.359 0.337 AV(Q+d)Z 0.399 0.377 AV(5+d)Z 0.407 0.384 Q5-CBS 0.417 0.394 TQ5-CBS 0.412 0.389 ΔCV –0.013 ΔDK –0.009 ΔZPE 0.053 Total 0.448a)/0.443b) 0.425a)/0.420b) Experiment 0.6 ± 0.1[7]/≤0.8[10]/0.58±0.05[11]/
0.5525(13)[12]Calculation 0.406[20]/0.382[20]/0.457[21]/0.54[11] 注:a)Q5-CBS+ΔCV+ΔDK+ΔZPE result.
b)TQ5-CBS+ΔCV+ΔDK+ΔZPE result.DownLoad:
CSV
绝热电子亲和能/eV UCCSD(T) RCCSD(T) AV(T+d)Z –0.098 –0.119 AV(Q+d)Z –0.073 –0.095 AV(5+d)Z –0.069 –0.091 Q5-CBS –0.062 –0.0839 TQ5-CBS –0.066 –0.0876 ΔCV –0.016 ΔDK –0.004 ΔZPE 0.070 Total –0.012a)/–0.016b) –0.034a)/–0.038b) Experiment 0.46±0.2[4]/–0.04[6] Calculation –0.007[21]/–0.059±0.061[24] 注:a)Q5-CBS+ΔCV+ΔDK+ΔZPE result.
b)TQ5-CBS+ΔCV+ΔDK+ΔZPE result.DownLoad:
CSV
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[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35]
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