1.Please use ChatGPT to explore a thematic series of questions within the scope of computational chemistry and follow up with further inquiries about any unfamiliar terms ( except homework )
2.Calculate the structure and frequencies of XHn (X = H~Ne) by using B3LYP theoretical method with 6-31+G(d,p) then compare with the experimental values.
| AHn | B3LYP/6-31+G(d,p) | Expt |
| H2 | 0.734 | 0.741 |
| LiH | 1.623 | 1.595 |
| BeH2 | 1.328 | 1.326 |
| BH3 | 1.185 | 1.19 |
| CH4 | 1.086 | 1.087 |
| NH3 | 1.012 | 1.012 |
| H2O | 0.963 | 0.958 |
| HF | 0.927 | 0.917 |
| AHn | B3LYP/6-31+G(d,p) | MP2/6-31+G(d,p) | Expt |
| H2 | - | - | - |
| LiH | - | - | - |
| BeH2 | 180 | 180 | 180 |
| BH3 | 120 | 120 | 120 |
| CH4 | 109.471 | 109.471 | 109.5 |
| NH3 | 107.2 | 108.2 | 106.7 |
| H2O | 105.72 | 105.4 | 104.5 |
| HF | - | - |
| Wavenumber(cm-1) | ||||||||||
| H2 | B3LYP | 4465.7 | ||||||||
| EXP | 4401.2 | |||||||||
| Error | 64.5 | |||||||||
| LiH | B3LYP | 1401.1 | ||||||||
| EXP | 1405.5 | |||||||||
| Error | -4.4 | |||||||||
| BeH2 | B3LYP | 735.9 | 735.9 | 2038.3 | 2260.6 | |||||
| EXP | 697.9 | 697.9 | 2159.1 | |||||||
| Error | 38.0 | 1340.4 | 101.5 | |||||||
| BH3 | B3LYP | 1157.6 | 1205.3 | 1205.3 | 2576.8 | 2704.4 | 2704.4 | |||
| EXP | 1147.5 | 1196.7 | 2601.6 | 2601.6 | 2601.6 | |||||
| Error | 10.1 | 8.6 | -24.8 | 102.8 | 102.8 | |||||
| CH4 | B3LYP | 1347.3 | 1347.3 | 1347.3 | 1563.8 | 1563.8 | 3037.1 | 3150.0 | 3150.0 | 3150.0 |
| EXP | 1306.0 | 1534.0 | 2917.0 | 3019.0 | ||||||
| Error | 41.7 | 30.6 | 30.6 | 120.3 | 131.7 | |||||
| NH3 | B3LYP | 1000.3 | 1673.6 | 1673.6 | 3484.7 | 3627.6 | 3627.6 | |||
| EXP | 950.0 | 1627.0 | 1627.0 | 3337.0 | 3444.0 | 3444.0 | ||||
| Error | 50.3 | 46.6 | 147.5 | 183.6 | ||||||
| H2O | B3LYP | 1603.2 | 3809.6 | 3931.5 | ||||||
| EXP | 1648.5 | 3832.2 | 3942.5 | |||||||
| Error | -45.3 | -22.6 | -11.0 | |||||||
| HF | B3LYP | 4069.8 | ||||||||
| EXP | 4138.4 | |||||||||
| Error | -68.6 | |||||||||
鍵長和鍵角計算結果和實驗值很接近，因此沒有做誤差分析。
3.Calculate the single point energy of XHn (X = H~Ne) by using CCSD(T) theoretical method with aug-cc-pVTZ ( the structure obtained from the previous homework ), and then use those energy to calculate the standard enthalpy of formation (ΔH°f) then compare with the experimental values.
Table.enthalpy of formation (ΔH°f) Unit:Kcal/mol
| Hx | EXPT | CCSD(T)/aug-ccpVTZ | ERROR |
| H2 | 0.0 | 3.7 | 3.7 |
| LiH | 33.6 | 34.5 | 0.9 |
| BeH2 | 30.0 | 36.9 | 6.9 |
| BH3 | 21.0 | 22.7 | 1.7 |
| CH4 | -17.9 | -20.0 | -2.1 |
| NH3 | -11.0 | -12.9 | -1.9 |
| H2O | -57.8 | -46.9 | 10.8 |
| HF | -65.3 | -55.9 | 9.5 |
| MAE | 10.2 |
MAE:10.2(Kcal/mol)
Reference:Computational Chemistry Comparison and Benchmark DataBase
CCSD(T)TAE_b.xlsx