A six-dimensional variational code, recently presented for the determination of the rovibrational energy levels of formaldehyde, has been used to refine a quartic potential surface of thioformaldehyde and simultaneously to optimize its geometry. The parameters have been adjusted to obtain as good agreement as possible with the known J = 0 vibrational energy levels and the corresponding observed J = 1 rotational lines of both H2CS and D2CS, where known. This is a highly nonlinear problem, and it is not possible to refine separately the geometry and force field. We have simultaneously optimized the HCS bond angle, the quadratic force field, and a partial cubic and quartic force field. Fermi and Coriolis resonances have been reproduced. The predicted geometry is CH = 1.0856 Å, CS = 1.6110 Å, HCS = 121.88 degrees. Predictions are made for overtones and combination bands of H2CS and D2CS. Furthermore, a prediction is made for the unobserved fundamental nu5 of D2CS, which lies very close to 3nu6. Copyright 1998 Academic Press.

中文翻译：

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硫代甲醛的几何和力场

最近提出的用于确定甲醛的旋转能级的六维变分代码已用于细化硫代甲醛的四次势面并同时优化其几何形状。已调整参数以尽可能与已知的 J = 0 振动能级和相应的观察到的 H2CS 和 D2CS 的 J = 1 旋转线（已知）保持一致。这是一个高度非线性的问题，不可能单独细化几何和力场。我们同时优化了 HCS 键角、二次力场以及部分三次和四次力场。已再现费米和科里奥利共振。预测的几何形状为 CH = 1.0856 Å，CS = 1.6110 Å，HCS = 121.88 度。对 H2CS 和 D2CS 的泛音和组合频带进行了预测。此外，还对 D2CS 的未观察到的基本 nu5 进行了预测，该 nu5 非常接近 3nu6。版权所有 1998 学术出版社。