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对《ＣＲＣ物理与化学手册》（第７７版）中第三周期以前的无机双原子分子，当其理论优化构型的相对误差大于２％时，分别在实验构型和最大偏差的理论构型下，计算了ＱＣＩＳＤ（Ｔ）／６－３１１＋Ｇ（３ｄｆ，２ｐ）能量并作了比较．结果表明，大多数能量的差别在４．２ｋＪ·ｍｏｌ~（－１）以内．由此说明，目前一般采用的构型优化理论方法，多数情况下不至于明显影响单点高级别从头算的计算精度．同时还发现，Ｇ２（ＱＣＩ）的高级从头算方法 ＱＣＩＳＤ（Ｔ）／６－３１１＋Ｇ（３ｄｆ，２ｐ），在实验构型下，并未给出最低的分子能量，ＭＰ２（ｆｕｌｌ）构型优化方法未能给出优化键长普遍的好结果，特别是对ＣＮ、ＣＰ和ＳＩＮ这种“４－５价电子结构”分子的偏差随基组增大而增大，导致较大的单点能量偏差．ＭＰ２（ｆｕｌｌ）／６－３１Ｇ（ｄ， ｐ）优化Ｏ_２和Ｎ_２的键长误差较大，导致单点能量偏差接近４，２ ｋＪ·ｍｏｌ~（－１），而ＭＰ２（ｆｕｌｌ）／６－３１１Ｇ（ｄ，ｐ）则较好地改善了它们的构型和ＱＣＩＳＤ（Ｔ）／６－３１１＋Ｇ（３ｄｆ，２ｐ）能量．ＢＮ（~（３）∏）的实验键长 １２８． １ｐｍ可能有误，有待进一步测定．
For the inorganic diatomic molecules before the third cycle in Handbook of CRC Physics and Chemistry (77th Edition), when the relative error of the theoretical optimized configuration is more than 2%, the theoretical configurations of the experimental configuration and the maximum deviation The energy of QCISD (T) / 6-311 + G (3df, 2p) was calculated and compared. The results show that most of the energy difference is within 4.2kJ · mol ~ (-1). This shows that the current general configuration optimization theory method, in most cases will not significantly affect the single-point high-level ab initio calculation accuracy. At the same time, we also found that QCISD (T) / 6-311 + G (3df, 2p), an advanced ab initio method of G2 (QCI), did not give the lowest molecular energy under the experimental configuration. The general results of optimization of the bond lengths are not given. In particular, the deviation of the “4-5 valence electron structure” molecules such as CN, CP and SIN increases with the increase of the base group, resulting in a large single point energy deviation . MP2 (full) / 6-31G (d, p) optimized the large error of bond length between O 2 and N 2, resulting in a single point energy deviation close to 4,2 kJ · mol -1, while MP2 (full) 311G (d, p) improved their configurations and QCISD (T) / 6-311 + G (3df, 2p) energies better. The experimental bond length of BN (~ (3) Π) is 128. 1pm may be wrong, pending further testing.