Terms of Service

1. Acceptance of Terms

By accessing or using SiestaStudio ("the Service"), operated by Arsalan Akhtar (the "Provider"; see §13 for full identity), you agree to be bound by these Terms of Service. If you do not agree to these terms, please do not use the Service.

2. Description of Service

SiestaStudio is a web-based platform for building and analyzing SIESTA density functional theory (DFT) simulations. The Service provides a visual interface for configuring simulation parameters, importing crystal structures, generating input files (.fdf), building multi-step workflows, managing pseudopotentials, running convergence studies, applying presets, validating inputs, and analyzing SIESTA output files including SCF convergence, band structures, DOS, and PDOS.

3. User Accounts

You may create an account using email/password or third-party authentication providers (Google, GitHub; ORCID is temporarily disabled). You are responsible for maintaining the confidentiality of your account credentials and for all activities that occur under your account. Processing of your personal data in connection with your account is described in our Privacy Policy, which forms an integral part of these Terms by reference.

4. Acceptable Use

You agree to use the Service only for lawful purposes related to scientific research and computational materials science. You may not:

• Use the Service for commercial purposes, resale, or incorporation into for-profit products (see Beta Status notice above)
• Use the Service for any illegal purpose, or to infringe the rights of third parties (including intellectual-property and privacy rights)
• Upload personal data of other individuals without a lawful basis under the GDPR or equivalent applicable law
• Attempt to gain unauthorized access to the Service, its underlying infrastructure, or other users' accounts
• Interfere with or disrupt the Service (DoS attempts, abusive crawling, automated scripting beyond documented API limits, evasion of rate limits or bot-protection)
• Reverse-engineer the Service's internal APIs, security mechanisms, or rate-limit thresholds for the purpose of circumvention
• Use the Service's HPC connections or compute features for cryptocurrency mining or any workload unrelated to materials science research
• Upload malicious content or code (malware, executable payloads, phishing kits, etc.)

5. Intellectual Property

The input files, calculations, analyses, and other content you generate using SiestaStudio belong to you. The Service itself, including its design, code, and documentation, is the intellectual property of Arsalan Akhtar. The five algorithmic libraries that power the Service (@siestastudio/core, structures, pseudos, bands, workflows) are published separately under the Apache License 2.0; the application code itself is not currently released under an open-source licence.

6. Data Storage and Privacy

We store your account information and saved calculations on a self-hosted server located in Germany (EU). You may delete your account and all associated data at any time through your profile settings (Profile → Danger Zone → Delete Account) or export your data as a ZIP archive (Profile → Danger Zone → Export My Data). Full details of how we collect, use, store, and protect your personal data — including the legal basis for each processing activity, the sub-processors we rely on, and your rights under the GDPR — are set out in our Privacy Policy.

Documentation assistant

The documentation assistant is provided as-is to help you use SIESTA and SiestaStudio; its answers may be imperfect, so verify them against the cited sources. We store your assistant questions and their answers as described in our Privacy Policy.

7. Disclaimer of Warranties

The Service is provided "as is" and "as available" without warranties of any kind, express or implied, including without limitation warranties of merchantability, fitness for a particular purpose, or non-infringement. We do not guarantee that the generated input files will produce correct or expected results in SIESTA calculations. Output analysis features (SCF convergence, band structures, DOS, PDOS, transmission, dispersion, and property extraction) are provided for convenience and may contain inaccuracies; they do not constitute scientific validation. Input diagnostics and health scores are advisory only. Users are responsible for independently verifying all input parameters, analysis results, and scientific conclusions before relying on them in published work or any decision of consequence.

8. Limitation of Liability

To the maximum extent permitted by applicable law, Arsalan Akhtar shall not be liable for any indirect, incidental, special, consequential, or punitive damages — including but not limited to loss of profits, loss of data, business interruption, incorrect simulation results, or damage to research outputs — arising from or related to your use of the Service, whether based on contract, tort (including negligence), strict liability, or any other legal theory.

Statutory carve-outs: Nothing in this section excludes or limits any liability that cannot lawfully be excluded under applicable law, including (a) liability for death or personal injury caused by negligence, (b) liability for fraud or fraudulent misrepresentation, and (c) any rights that consumers may have under Spanish consumer-protection law (Real Decreto Legislativo 1/2007, Ley General para la Defensa de los Consumidores y Usuarios) or analogous EU consumer-protection law in their country of residence.

9. Account Suspension and Termination

We may suspend or terminate your account in either of the following ways:

• (a) Immediately, without prior notice — if you materially breach these Terms or engage in conduct that risks harm to the Service, its operator, or other users. This includes (without limitation) fraud, abuse, security probing beyond bona-fide research, illegal use, evasion of rate limits or bot-protection, or any violation of §4 Acceptable Use.
• (b) On reasonable prior notice (typically 30 days) — for any other reason at our sole discretion, including but not limited to: prolonged inactivity, legal or regulatory constraints (including sanctions or export-control restrictions), discontinuation of the Service or of a feature you rely on, or where continued provision would impose unreasonable cost or risk on us as a free, non-commercial academic beta operator.

We will provide a statement of reasons for any suspension or termination decision, in accordance with Article 17 of the EU Digital Services Act (Regulation (EU) 2022/2065). You may appeal a decision by emailing the contact in §14; we will review the appeal in good faith within a reasonable time and confirm the outcome in writing.

If you are dissatisfied with our handling of an appeal, you may also seek out-of-court dispute resolution through the European Commission's Online Dispute Resolution platform at ec.europa.eu/consumers/odr (Art. 21 DSA), or by contacting a certified out-of-court dispute-settlement body of your choice.

We may also refuse to create an account at signup, in our sole discretion, where we reasonably believe doing so is necessary to comply with law, protect the Service or other users, or prevent abuse. Pre-contract refusal does not require a statement of reasons because no contract has yet been formed.

You may delete your account at any time from your profile settings; deletion is processed according to the cascade described in our Privacy Policy §12. Suspension or termination by us does not affect your rights under the Privacy Policy to access, export, or erase your personal data — those rights survive the end of our contractual relationship.

10. Discontinuation of the Service

SiestaStudio is provided as a free, non-commercial academic beta operated by a single individual (see §14 Provider Identity). We may discontinue the Service in whole or in part at any time, including by shutting down the website entirely.

If we shut down the Service entirely:

• We will give registered users at least 30 days' advance notice by email sent to your account email address (regardless of marketing preferences) and by posting a notice on the Service.
• During the notice period, the data-export feature (Profile → Danger Zone → Export My Data) will remain available so you can download a ZIP archive of your account contents under your right to data portability (Art. 20 GDPR).
• On the shutdown date, all accounts will be deactivated and personal data will be deleted in accordance with the right to erasure (Art. 17 GDPR), subject to the limited retention exceptions described in our Privacy Policy §12 (notably the 90-day audit-log TTL and any data we are required by law to retain).
• We may at our discretion transfer the open-source libraries (@siestastudio/core, structures, pseudos, bands, workflows) to a successor maintainer. User account data will not be transferred to any third party without your explicit consent.

If we discontinue only a specific feature (rather than the entire Service), we will give reasonable advance notice and, where appropriate, provide a migration path or feature-specific export option for the affected data.

No compensation, refund, or replacement service is owed in connection with any discontinuation, because the Service is provided free of charge. Any mandatory consumer rights you may hold under Spanish or EU law are not affected by this clause.

11. Governing Law and Jurisdiction

These Terms are governed by the laws of the Kingdom of Spain, without regard to its conflict-of-laws principles. Any dispute arising out of or in connection with these Terms or your use of the Service shall be subject to the exclusive jurisdiction of the competent courts of Barcelona, Spain.

If you are acting as a consumer resident in the European Union, this clause does not deprive you of the mandatory protection of the consumer-protection law of your country of residence, including the right to bring proceedings in the courts of that country (Article 18 of Regulation (EU) 1215/2012).

12. Changes to Terms

We may update these Terms from time to time. When we make material changes, we will show registered users a prominent notice in the Service the next time you sign in. Continued use of the Service after the effective date of an update constitutes acceptance of the updated Terms. The "Last updated" date at the top of this page always reflects the most recent revision.

13. Contact

For questions about these Terms of Service, contact us at sr.arsalan.akhtar@gmail.com.

14. Provider Identity