# EXESS vs TeraChem

> Compare EXESS and TeraChem for GPU-accelerated quantum chemistry. Performance, multi-GPU scaling, pricing, AMD support, and cloud access compared.

URL: https://exess.qdx.co/comparisons/exess-vs-terachem

TeraChem pioneered GPU-accelerated quantum chemistry and remains a strong choice for researchers with NVIDIA hardware. Its CASSCF and TDDFT implementations are well-regarded for excited-state work on GPUs.

EXESS builds on the GPU-first philosophy but extends it further: support for both NVIDIA and AMD GPUs, multi-node GPU scaling, larger system sizes, and free academic access via the cloud.

## Head-to-Head Comparison

| Feature | EXESS | TeraChem |
| --- | --- | --- |
| Pricing | Pay-as-you-go (compute included) | License (contact directly for pricing) |
| Free Academic Access | Yes | No |
| GPU Support | Native GPU (CUDA + HIP) | Native GPU (CUDA) |
| Methods | HF, DFT, RI-MP2, MBE | HF, DFT, CASSCF, TDDFT |
| Hardware | GPU clusters (NVIDIA + AMD) | NVIDIA GPU |
| Cloud Availability | Yes — browser-based | TeraChem Cloud (limited) |
| Parallel Scaling | Multi-node GPU (world first exascale calculation) | Multi-GPU single node |
| License | Proprietary (free academic) | Commercial |

## GPU Architecture & Hardware

Both EXESS and TeraChem are GPU-native codes, but they differ in hardware support and scaling. TeraChem supports NVIDIA CUDA GPUs and can use multiple GPUs on a single node. EXESS supports both NVIDIA (CUDA) and AMD (HIP) GPUs and scales across multi-node GPU clusters.

## Pricing & Access

TeraChem requires a commercial license, though no public price estimate is available.

EXESS is free for academic use and runs in the cloud — no GPU hardware purchase, CUDA driver management, or IT support needed. This makes high-performance GPU quantum chemistry accessible to groups without dedicated GPU infrastructure.

## When to Choose EXESS

- You need support for AMD GPUs (HIP)
- Your systems exceed 2,000 atoms
- You need multi-node GPU scaling
- You want cloud-based access without managing GPU hardware
- You want free academic access
- You have an existing compute allocation with an HPC cluster and want to use it most efficiently
- Speed is important

## When to Choose TeraChem

- You need GPU-accelerated CASSCF or TDDFT
- You're working on single-node multi-GPU setups with NVIDIA hardware

## Frequently Asked Questions

### How does EXESS compare to TeraChem for GPU performance?

Both are GPU-native codes with strong single-GPU performance. EXESS differentiates with multi-node GPU scaling (enabling larger calculations) and AMD GPU support via HIP.

### Does EXESS support AMD GPUs like TeraChem does not?

Yes. EXESS supports both NVIDIA GPUs (via CUDA) and AMD GPUs (via HIP). TeraChem only supports NVIDIA CUDA GPUs. This makes EXESS the better choice for institutions with AMD Instinct hardware.

### How much does TeraChem cost compared to EXESS?

TeraChem requires a commercial license, though no public price estimate is available. EXESS is free for academic use and available via the cloud, requiring no local GPU hardware or license fees.

### Which is better for ab initio molecular dynamics: EXESS or TeraChem?

TeraChem has established AIMD capabilities with GPU acceleration. EXESS has performed AIMD on systems with hundreds of thousands of atoms and supports single-point energy calculations, geometry optimizations, large-scale MBE workflows, and GPU-accelerated AIMD at unprecedented scale.