Excited-State Electronic Structure with Configuration Interaction Singles and Tamm-Dancoff Time-Dependent Density...

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Accurate excited-state calculations are crucial for understanding molecular properties and designing new materials.
• Traditional methods are computationally expensive, limiting the size of molecules that can be studied.
• Graphics Processing Units (GPUs) offer potential for accelerating these demanding calculations.

Purpose of the Study:

• To implement and evaluate configuration interaction singles (CIS) and time-dependent density functional theory (TDDFT) for excited-state calculations on a GPU-based platform.
• To assess the scalability and accuracy of GPU-accelerated methods for large molecular systems.
• To investigate the impact of numerical precision on the accuracy of GPU-based calculations.

Main Methods:

• Development and implementation of CIS and adiabatic linear response TDDFT methods within the GPU-accelerated TeraChem software.
• Utilized GPU-accelerated electron repulsion integrals and density functional quadrature integration.
• Performed benchmark calculations using CIS/6-31G and TD-BLYP/6-31G on oligothiophene dendrimers, photoactive yellow protein (PYP), and solvated PYP chromophore.

Main Results:

• Achieved significant speedups for CIS and TDDFT calculations through GPU acceleration.
• Enabled excited-state calculations on molecules of unprecedented size.
• Demonstrated that mixed-precision GPU integration yields highly accurate excitation energies, comparable to double-precision CPU results (within 0.0005 eV).

Conclusions:

• GPU-based implementation of CIS and TDDFT methods significantly enhances computational efficiency for excited-state calculations.
• The developed methods allow for ab initio studies of large and complex molecular systems.
• Mixed-precision integration on GPUs provides a computationally efficient yet numerically accurate approach for electronic structure calculations.