# EXESS — GPU-Accelerated Quantum Chemistry Software

> EXESS by QDX compresses a year of compute into hours. GPU-native quantum chemistry software that performed ab initio QMD simulations 1000x faster and larger than anything before.

URL: https://exess.qdx.co

## What is EXESS?

EXESS is flagship quantum chemistry software by QDX. It generates high-accuracy quantum chemistry data orders-of-magnitude faster using GPU acceleration. EXESS supports both NVIDIA (CUDA) and AMD (HIP) GPUs and scales across multi-node GPU clusters.

## Key Capabilities

- **Methods**: RHF, UHF, RI-HF, Kohn-Sham DFT, Double-Hybrid Functionals, RI-MP2 Correlation
- **Many-Body Expansion**: Up to 4th order (tetramers), covalent bond capping, fragment distance cutoffs
- **Molecular Dynamics**: Born-Oppenheimer AIMD, geometry optimization, QM/MM/ML regions, NVT/NPT thermostats
- **Hardware**: CUDA & HIP acceleration, multi-GPU scaling, multi-node MPI, GPU memory control
- **Scale**: Handles hundreds of thousands of atoms and millions of electrons
- **Performance**: 10–100x speedups over CPU-only codes; performed the world's first exascale quantum chemistry calculation

## Access

- **Browser-based**: Run calculations directly at https://exess.qdx.co/try — no installation required
- **Free for academics**: No license fees, no hardware procurement needed
- **Pay-as-you-go**: Compute included
- **HPC integration**: Can integrate with existing HPC cluster allocations

## About QDX

QDX is a computational chemistry company that integrates the world's fastest and largest-scale quantum mechanical simulation technology with supercomputing, artificial intelligence, and deep drug discovery expertise. QDX partners with leading pharmaceutical companies and academic institutions to advance the frontiers of computational chemistry and drug discovery.

## Comparison Pages

- [Quantum Chemistry Software Comparison](https://exess.qdx.co/comparisons/quantum-chemistry-software): Compare all major packages side-by-side
- [EXESS vs Gaussian](https://exess.qdx.co/comparisons/exess-vs-gaussian): GPU speed vs method breadth
- [EXESS vs ORCA](https://exess.qdx.co/comparisons/exess-vs-orca): Two free academic options compared
- [EXESS vs Q-Chem](https://exess.qdx.co/comparisons/exess-vs-qchem): Ground state vs excited state focus
- [EXESS vs TeraChem](https://exess.qdx.co/comparisons/exess-vs-terachem): GPU-native codes compared
- [Free Quantum Chemistry Software](https://exess.qdx.co/comparisons/free-quantum-chemistry-software): Open-source and free options