A global potential energy surface and dipole moment surface for silane

Area of Science:

• Computational Chemistry
• Molecular Spectroscopy
• Quantum Chemistry

Background:

• Accurate potential energy surfaces (PES) and dipole moment surfaces (DMS) are crucial for understanding molecular behavior.
• Silane (SiH4) is a fundamental molecule with applications in semiconductor manufacturing and materials science.

Purpose of the Study:

• To generate a high-accuracy nine-dimensional PES and DMS for silane (SiH4).
• To enable precise predictions of silane's spectroscopic properties, including vibrational and rotational energy levels and infrared spectra.

Main Methods:

• High-level ab initio theory, specifically explicitly correlated coupled cluster calculations with extrapolation to the complete basis set limit (CBS-F12(HL)).
• Inclusion of higher-level additive energy corrections (core-valence correlation, higher-order coupled cluster, scalar relativistic effects).
• Empirical refinement of the equilibrium geometry to minimize systematic errors in rotational energy levels.

Main Results:

• The generated PES (CBS-F12(HL)) achieves sub-wavenumber accuracy for fundamental term values of (28)SiH4 (RMS error of 0.63 cm(-1)).
• Calculated Si-H bond length shows excellent agreement with experimental and theoretical data.
• Vibrational transition moments, line intensities, and infrared spectra were computed, showing good agreement with experimental results despite a slight overestimation of line intensities by the DMS.

Conclusions:

• The new PES and DMS provide a highly accurate representation of silane's energetic and spectroscopic properties.
• The developed surfaces are recommended for future theoretical and experimental studies of silane.
• The study highlights the importance of high-level ab initio methods and careful treatment of corrections for accurate molecular modeling.