You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Theoretical study of the reaction of CH2XO (X = F, Cl, Br) radicals with the NO radical. In this paper, we focus on the multiple-channel reactions of CH(2)XO (X = F, Cl, Br) radicals with the NO radical by means of direct dynamic methods. All structures of the stationary points were obtained at the MP2/6-311+G(d,p) level and vibrational frequency analysis was also performed at this level of theory. The minimum energy path (MEP) was obtained via the intrinsic reaction coordinate (IRC) theory at the MP2/6-311+G(d,p) level, and higher-level energetic information was refined by the MC-QCISD method. The rate constants for the three hydrogen abstraction reaction channels over the temperature range 200-1,500 K were calculated by the improved canonical variational transition state theory (ICVT) with a correction for small-curvature tunneling (SCT). The rate constants calculated in this manner were in good agreement with the available experimental data, and the three-parameter rate-temperature formulae for the temperature range 200-1,500 K were k(1a)(T) = 0.32 × 10(-18) T(1.83) exp(1748.54/T), k(2a)(T) = 0.22 × 10(-19) T(2.19) exp(1770.19/T), k(3a)(T) = 0.88 × 10(-20) T(2.20) exp(1513.82/T) (in units of cm(3) molecule(-1) s(-1)).
{"Chemical": ["CH2XO", "F", "CH(2)XO", "hydrogen", "Cl", "Br", "NO"]}