Calculation of antineutrino spectrum corrections for sterile neutrino experimental searches

For SOX experiment with intense ¹⁴⁴Ce-¹⁴⁴Pr source, the antineutrino spectrum from two ¹⁴⁴Pr decay branches should be calculated with high precision. We analyze the factors that affect beta- and antineutrino spectrum and give methods for their calculation.