Steering Committee Terms of Reference

1. Purpose and Scope

1.1 About ASE

The Atomic Simulation Environment (ASE) is a set of tools and Python modules for setting up, manipulating, running, visualizing and analyzing atomistic simulations. It is an international, open-source project where everybody is encouraged to participate and contribute. The code is freely available under the GNU LGPL license.

1.2 Purpose of the Steering Committee

The ASE Steering Committee (ASE-SC) is established to provide strategic leadership and governance for the ASE project. The committee’s primary responsibilities are to:

1. Make decisions on long-term goals and strategic direction for the ASE project
2. Define and maintain guidelines for the ASE software project
3. Seek support and funding for ongoing development and sustainability
4. Represent the interests of the ASE user and developer community
5. Provide guidance and support to the Technical Sub-Committee on significant decisions
6. Ensure the project remains open, inclusive, and aligned with community needs

The Steering Committee serves to “shield” maintainers from difficult community decisions while ensuring technical choices align with broader project goals.

2. Committee Structure

2.1 Steering Committee (ASE-SC)

The Steering Committee comprises members drawn from the international atomistic simulation community, representing diverse institutions, career stages, and areas of expertise. Members should collectively represent:

• Major user communities and application domains
• Key institutional stakeholders and funders
• Geographic and institutional diversity
• A balance of experience levels

Composition

The committee should consist of 12–20 members to ensure diverse representation while remaining effective for decision-making. The committee should not exceed 20 members; it is the committee’s responsibility to manage its size within this limit when welcoming new members.

Chair

The Chair is responsible for:

• Convening and facilitating committee meetings
• Setting meeting agendas in consultation with members
• Ensuring decisions are documented and actioned
• Acting as the primary point of contact for the committee
• Liaising with the Technical Sub-Committee

2.2 Technical Sub-Committee (ASE-TSC)

The Technical Sub-Committee leads the day-to-day development of the code, including gate-keeping of contributions via merge requests. The ASE-TSC operates with greater autonomy on technical matters but may escalate significant decisions to the full Steering Committee.

The ASE-TSC is responsible for:

• Managing the codebase, releases, and infrastructure
• Reviewing and merging contributions
• Maintaining documentation and test coverage
• Making technical architecture decisions
• Reporting progress to the Steering Committee

3. Membership

3.1 Eligibility

Membership is open to individuals who have demonstrated sustained commitment to the ASE project through one or more of:

• Significant code contributions
• Documentation development
• Community support and engagement
• Scientific applications advancing ASE capabilities
• Institutional support or funding

3.2 Term Limits

Role	Term
Steering Committee Member	5 years, renewable once (maximum 10 years continuous service)
Chair	2 years, renewable once (maximum 4 years as Chair)
Technical Sub-Committee Member	No fixed term; renewable based on continued active contribution

Rationale: Term limits ensure fresh perspectives, prevent concentration of authority, and create opportunities for emerging community members. The longer 5-year term recognises that contributors to open-source projects typically remain involved for extended periods, while the two-term maximum balances continuity with renewal. Technical Sub-Committee members have no fixed term limit as they are the active code maintainers; their continued membership depends on ongoing contribution to the project.

TSC Membership: Members of the Technical Sub-Committee are full members of the Steering Committee for the duration of their TSC role, with the same rights and responsibilities as other SC members (including voting rights). TSC membership on the SC is independent of SC term limits; TSC members do not count against their SC term allocation while serving on the TSC.

Initial Terms: To avoid all founding members departing simultaneously, initial Steering Committee members will be randomly assigned to staggered terms of 3, 4, or 5 years. This ensures orderly rotation begins from the outset.

Maximum Size: The committee should not exceed 20 members. The committee is responsible for managing its own size within this limit when considering new appointments.

3.3 Appointment Process

New Members

1. Nominations may be made by any current committee member or self-nominated by community members
2. Nominees should provide a brief statement of their interest and relevant experience
3. The committee will review nominations annually and approve new members by consensus or, if necessary, simple majority vote
4. Priority will be given to candidates who enhance the committee’s diversity and coverage of the ASE user community

Chair Selection

1. The outgoing Chair (or a nominated member) will call for expressions of interest
2. Candidates will present their vision for the committee
3. Selection is by consensus or, if necessary, simple majority vote of the Steering Committee
4. The incoming Chair should have prior experience as a committee member

3.4 Departure, Removal and Succession

Members may step down at any time by notifying the Chair. Members who do not participate in two consecutive meetings without apology may be contacted to discuss their continued membership.

Removal: In exceptional circumstances where a member is persistently inactive or whose conduct is detrimental to the project, the committee may vote to remove that member. Removal requires a two-thirds majority of the committee (excluding the member in question). The member should be given an opportunity to respond before any vote is taken.

When members depart, the committee should actively seek replacements to maintain appropriate representation, subject to the maximum size limit.

4. Meetings and Decision-Making

4.1 Meeting Frequency

• Steering Committee: Meets at least twice per year (targeting every 6 months), with flexibility for additional meetings as needed
• Technical Sub-Committee: Communicates more frequently as required for ongoing development (e.g., monthly or bi-weekly check-ins)

4.2 Quorum

A quorum for Steering Committee decisions requires participation of at least 50% of current members.

4.3 Decision-Making

The committee operates by consensus where possible. When consensus cannot be reached:

• Decisions require a simple majority of those present (assuming quorum)
• The Chair has a casting vote in case of a tie
• Significant decisions (e.g., major API changes, governance amendments) require a two-thirds majority

4.4 Meeting Records

Summary minutes of Steering Committee meetings will be made public after review by members. Minutes will record agreed outcomes and summaries of discussions, and will be hosted in the ASE GitLab organisation.

5. Communication

5.1 Internal Communication

A committee mailing list will be maintained for communication between meetings. This provides a means for the Technical Sub-Committee to seek advice from the full committee.

5.2 External Communication

• The ASE website (https://ase-lib.org) will list current committee members and their affiliations
• A contact email will be provided for community members to raise matters with the committee
• Major decisions and announcements will be communicated via the ASE website and mailing lists

6. Relationship with Other Bodies

6.1 ASE Foundation

The committee supports the establishment of an ASE Foundation (or equivalent legal entity) to receive funding for project activities. The Steering Committee will oversee the use of any funds received, with day-to-day management delegated as appropriate.

6.2 CECAM and Partner Organisations

The committee will maintain relationships with organisations such as CECAM, Psi-k, and NumFOCUS to support workshops, documentation sprints, and other community activities.

7. Amendments

These Terms of Reference may be amended by a two-thirds majority vote of the Steering Committee. Proposed amendments should be circulated at least two weeks before the meeting at which they will be considered.

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Document History

• v1.0 (August 2025): Initial draft following the inaugural ASE Steering Committee meeting on 20 August 2025.
• v2.0 (January 2026): Reviewed at Meeting #2 and considered suitable for adoption.
• v3.0 (June 2026): Incorporates the clarification agreed at Meeting #2 (action A21) that TSC members are full Steering Committee members with voting rights. Presented for formal adoption at Meeting #3.

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Addendum A: Initial Term Allocations

As specified in Section 3.2, founding Steering Committee members are randomly assigned to staggered initial terms of 3, 4, or 5 years. The following allocations were determined by random selection at Meeting #2 (February 2026).

Initial Term	Members
3 years (expires 31/12/2028)	Andrew Peterson, Elena Gelžinytė, Michael Herbst, Paul Erhart, Xing Wang
4 years (expires 31/12/2029)	Alin-Marin Elena, Andrew Rosen, Gábor Csányi, Hanna Türk, Karsten Wedel Jacobsen
5 years (expires 31/12/2030)	Bjørk Hammer, James Kermode (Chair), Kristian Thygesen, Lars Pastewka, Michele Ceriotti

All terms commence from February 2026. Upon expiry of an initial term, members may be re-appointed for a standard 5-year term, subject to the maximum 10-year continuous service limit.

Note: Technical Sub-Committee members (Adam Jackson, Ask Hjorth Larsen, Yuji Ikeda) serve on the Steering Committee for the duration of their TSC role and are not subject to SC term limits.