chem-dft-orca-advanced-calculation

chem-dft-orca-advanced-calculation is a skill for Claude Code, Codex from learningmatter-mit/AtomisticSkills. It costs 57 tokens per session (1,989 once invoked), scanned A, original, MIT.

A way to create and run custom ORCA quantum-chemistry calculations when standard wrappers do not expose the required settings. ORCA is software for calculating molecular energies and electronic properties.

In plain words
What is it for?
Use it to write custom ORCA input files and run specialized electronic-structure calculations beyond ordinary single-point energy or geometry-optimization workflows.
Why use it?
It supports advanced methods and options such as excited states, relativistic effects, multi-reference calculations, NMR, and EPR.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is For **standard DFT single-point** calculations (energy, gradients, Hessian), use the [singlepoint skill](../chem-dft-orca-singlepoint/SKILL.md) instead. For **g.

Good fit Use it to write custom ORCA input files and run specialized electronic-structure calculations beyond ordinary single-point energy or geometry-optimization workflows.

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Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/learningmatter-mit/AtomisticSkills
agentmods
npx agentmods add skills/learningmatter-mit/atomisticskills/chem-dft-orca-advanced-calculation

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for chem-dft-orca-advanced-calculation

README.md
[![agentmods](https://agentmods.dev/badge/skills/learningmatter-mit/atomisticskills/chem-dft-orca-advanced-calculation.svg)](https://agentmods.dev/skills/learningmatter-mit/atomisticskills/chem-dft-orca-advanced-calculation)
Your own site
<a href="https://agentmods.dev/skills/learningmatter-mit/atomisticskills/chem-dft-orca-advanced-calculation"><img src="https://agentmods.dev/badge/skills/learningmatter-mit/atomisticskills/chem-dft-orca-advanced-calculation.svg" alt="Measured on agentmods" height="20"></a>
Per session 57 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,989 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00057 $0.01989
Opus 5 $0.00028 $0.00994
Sonnet 5 $0.00011 $0.00398
Haiku 4.5 $0.00006 $0.00199

Measured 7d ago against content hash c3cbd6edc953, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

chem-dft-orca-advanced-calculation scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/parse_orca_output.py, scripts/run_orca_input.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agents/skills/chem-dft-orca-advanced-calculation/SKILL.md · 171 lines

How it starts

The opening of the file, as written. The whole thing — 171 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Advanced ORCA Calculation

Goal

Enable advanced ORCA quantum chemistry calculations by constructing a custom ORCA input file from scratch. This skill covers methods and features not available through the SCINE wrapper, including multi-reference methods, excited states, relativistic effects, advanced SCF settings, NMR/EPR properties, and more.

[!IMPORTANT] For standard DFT single-point calculations (energy, gradients, Hessian), use the singlepoint skill instead. For geometry optimization, use the optimization skill. This skill is for cases where those wrappers do not expose the needed method or settings.

1. Prerequisites

  • Conda environment: orca-agent with ase installed (SCINE not required for this skill)
  • ORCA binary: The environment variable ORCA_BINARY_PATH must point to the ORCA executable
    export ORCA_BINARY_PATH=/path/to/orca
    
  • ORCA documentation: Consult the ORCA 6.1 tutorials for method-specific input syntax, keyword blocks, and recommended settings

2. Workflow

Step 1: Understand the user's request

Identify the target method, property, and system. Determine which ORCA keywords and blocks are needed. If unsure, consult the tutorials linked above for the specific method.

Step 2: Write the ORCA input file

Create a .inp file following ORCA input syntax. Every input file should include:

Mandatory elements:

  • A keyword line starting with ! specifying the method, basis set, and job type
  • A *xyzfile entry referencesing an external .xyz file

Strongly recommended elements:

  • %pal nprocs N end: parallelization (always set this to avoid single-core runs)
  • %maxcore M: memory per core in MB (e.g. 4000 for 4 GB per core)

Example — TD-DFT excited states:

! B3LYP def2-TZVP TightSCF
%pal nprocs 4 end
%maxcore 4000

%tddft
  NRoots 10
  MaxDim 5
end

* xyzfile 0 1 molecule.xyz

Read the full file on GitHub · 171 lines

Files

What ships with it

4 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 7d ago First seen · 171 lines · 57 tokens per session scan A c3cbd6edc953

Subscribe to this mod's changes

chem-dft-orca-advanced-calculation is a skill published in the GitHub repository learningmatter-mit/AtomisticSkills (161 stars, last pushed 4d ago), licensed MIT. It adds 57 tokens to every session and 1,989 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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