A new scheme to calculate isotope effects

Area of Science:

• Computational Chemistry
• Theoretical Chemistry

Background:

• Calculating isotope effects is crucial for understanding chemical reactions and molecular properties.
• Full Hessian calculations at high theory levels can be computationally expensive.

Purpose of the Study:

• To develop an efficient and accurate method for calculating isotope effects.
• To reduce the computational cost associated with determining isotope effects.

Main Methods:

• A new scheme is proposed to calculate isotope effects.
• Only selected frequencies at the target level of theory are computed.
• Frequency selection is guided by Hessian analysis from a lower theory level.

Main Results:

• Accurate isotope effects are obtained without computing the full Hessian at the target level.
• The calculated frequencies demonstrate high accuracy.
• The proposed scheme converges to the correct isotope effect.

Conclusions:

• The new method provides an accurate and computationally efficient way to calculate isotope effects.
• This approach significantly reduces the burden of high-level electronic structure calculations.