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In this article , we show that in combination with a recent reparametrization , the approximate DFT method , DFTB , is able to describe the effects of hydrogen bonding on the C [ double bond , length as m - dash ] O stretch vibration in carboxylic acids reliably and agrees well with full DFT results .
 Chemical: hydrogen; Chemical: C; Chemical: O; Chemical: carboxylic acids
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; Chemical: C; Chemical: O; Chemical: carboxylic acids