Senior Software Engineer with Security Clearance

Job Category: Engineering Requisition Number: SENIO001459 Apply now Posting Details *

• Posted: November 2, 2026
• Full-Time
• Remote
• Locations Showing 1 location NM - Remote N/A N/A, NM 00000, USA NM - Remote N/A N/A, NM 00000, USA +0 more locations less locations Job Details Description CeLeen, an operating firm of Command Holdings, is seeking a Senior Software Engineer to support a potential contract within the Department of Energy (DOE). The Senior Software Engineer will provide virtual scientific computing support sustaining a mission-critical computational framework for a Carlsbad, New Mexico site. This role will provide expertise in computer science methods and strong written communication skills to support an existing computational framework. The individual will support sustainment, modernization, performance optimization, HPC readiness, and transition support for evolving three-dimensional modeling capabilities, including software development, analysis, refactoring, verification and validation, documentation, performance improvement, platform portability, workflow reproducibility, and migration readiness for Linux-based computing environments. Expected salary range: $130,000 - $170,000 Work Environment:
• Ability to sit at a computer terminal for an extended period of time.
• Ability to work in confined areas.

Physical Demands

• While performing the responsibilities of the job, the employee is required to sit, stand, talk, and hear.
• Employee is often required to sit and use their hands and fingers to operate a computer.
• Reasonable accommodations may be made to enable individuals with disabilities to perform the essential functions.

Travel

• 0-10% / Occasional travel. CeLeen, an operating firm of Command Holdings, is a tribally-owned firm providing management consulting services to U.S. government agencies. Pursuant to PL 93-638, as amended, preference will be given to qualified Native Americans and spouses in all phases of employment. At CeLeen, our employees are the embodiment of our success as a firm. Our team is comprised of a tenacious group of professionals located across the globe. It includes military veterans and spouses of active duty troops, former federal employees, policy experts, academics, attorneys, and technical and business experts, all of whom share a strong work ethic and the skills to succeed in both collaborative and independent environments. CeLeen is invested in the long-term success of both our clients and colleagues for the right reasons. Our dedication to putting good government into practice is underpinned by a merit-based culture that measures success by productivity and credibility. CeLeen will provide reasonable accommodations to applicants who are unable to utilize our online application system due to a disability. Please send your request to the Human Resources Team. CeLeen is committed to equal employment opportunity based on merit. We recruit, employ, train, compensate, and promote without regard to race, religion, color, national origin, age, sex, disability, protected veteran status, or any other basis protected by applicable federal, state, or local law, and in accordance with EO 14173 and Federal Employment Laws: Equal Employment Opportunity and Employee Polygraph Protection Act.  CeLeen's Affirmative Action Program is available to any employee or applicant for employment for inspection upon request, to the extent required by federal regulations. The Affirmative Action Program can be accessed during normal business hours by making an appointment with the Human Resources Team. Basic Requirements
• Master's degree in computer science, engineering, or a related discipline such as environmental science, mathematics, or physics //OR// Bachelor's degree in a related discipline with 10 years of relevant experience.
• Ability to obtain and maintain a DOE Q clearance.
• Minimum of 5 years of experience in computational modeling, software development, and software documentation, including legacy software and systems.
• Experience in one or more technical and business domains.
• Experience programming in mixed-language scientific software environments, including Fortran, Python, and C and/or C++.
• Experience working in GNU/Linux or equivalent Linux-based development environments and associated build, compilation, and debugging toolchains.
• Experience with high-performance computing (HPC) systems.
• Experience using HPC job schedulers, such as Slurm or equivalent workload management systems.
• Must be able to demonstrate relevant project experience within the past five years.
• Must have hands-on experience in project completion involving computational modeling and software development performed in a regulated, safety-critical, or other high-consequence computational environment, consistent with the type of experience required under this role.
• Exceptional customer relationship management and team building skills.
• Advanced organizational and leadership skills.
• Outstanding communication skills, influencing abilities, and client focus.
• Professional proficiency in English is required.
• Demonstrated proficiency in using all Microsoft Office applications.
• Must be a U.S. Citizen.
• Ability to access federal facilities in compliance with Real ID. More information about Real ID can be found here: https://www.dhs.gov/real-id/about-real-id and at https://www.tsa.gov/travel/security-screening/identification.
• Applicants must be currently authorized to work in the United States on a full-time basis. CeLeen will not sponsor applicants for work visas for this position.

Preferred Qualifications

• Master's Degree.
• Current, active DOE Q clearance. Benefits CeLeen offers a competitive benefits plan including:
• Health, Dental, and Vision Insurance
• Flexible Spending Accounts
• Life and Disability Insurance
• 401(k)
• Paid Time Off
• Paid Holidays
• Employee Assistance Program
• Pet Insurance *Eligibility requirements apply Qualifications Skills Behaviors : Motivations : Education Experience Licenses & Certifications Equal Opportunity Employer/Protected Veterans/Individuals with Disabilities This employer is required to notify all applicants of their rights pursuant to federal employment laws.

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