Two-center harmonic oscillator basis for Skyrme-DFT calculations (I): formalism and Proof of Principle Adrián Sánchez-Fernández, Jacek Dobaczewski, Xuwei Sun and Herlik Wibowo Eur. Phys. J. A, 61 6 (2025) 138 Published online: 17 June 2025 DOI: 10.1140/epja/s10050-025-01605-6