{'fraction_non_alphanumeric': 0.030303030303030304, 'fraction_numerical': 0.01443001443001443, 'mean_word_length': 5.034782608695652, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Surface states and negative electron affinity in polyethylene.

First-principles calculations are used to investigate the electronic properties of the surfaces of polyethylene. The calculations support the experimental evidence of a negative electron affinity, with calculated values of -0.17 eV and -0.10 eV for surfaces with chains perpendicular and parallel to the surface normal, respectively. Both surfaces exhibit a surface state with binding energy -1.2 +/- 0.5 eV with respect to the bulk polyethylene conduction band minimum. Implications of these findings on spectroscopy, as well as on the transport and aging properties of polyethylene for high-voltage applications, are discussed.