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However , when this hydrogen bond is eliminated , which better mimics the DNA environment , a small ( < 5 kJ mol ( - 1 ) ) anti / syn energy difference is predicted .
 Chemical: hydrogen
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: hydrogen