  Based on structure prediction method, the machine learning method is used
instead of the density function theory (DFT) method to predict the material
properties, thereby accelerating the material search process. In this paper, we
established a data set of carbon materials by high-throughput calculation with
available carbon structures obtained from the Samara Carbon Allotrope Database.
We then trained an ML model that specifically predicts the elastic modulus
(bulk modulus, shear modulus, and the Young's modulus) and confirmed that the
accuracy is better than that of AFLOW-ML in predicting the elastic modulus of a
carbon allotrope. We further combined our ML model with the CALYPSO code to
search for new carbon structures with a high Young's modulus. A new carbon
allotrope not included in the Samara Carbon Allotrope Database, named Cmcm-C24,
which exhibits a hardness greater than 80 GPa, was firstly revealed. The
Cmcm-C24 phase was identified as a semiconductor with a direct bandgap. The
structural stability, elastic modulus, and electronic properties of the new
carbon allotrope were systematically studied, and the obtained results
demonstrate the feasibility of ML methods accelerating the material search
process.
