| Porous Aromatic Frameworks materials（PAFs）have great potential in gas adsorption due to their lower density,high specific surface area,tunable pore structure and function,and a highly stable carbon-carbon connected framework.With the rapid development of computer performance and molecular simulation technology,the computer-assisted screening and design of highly efficient new porous materials can improve development efficiency and reduce synthesis costs,thus possessing significant theoretical and practical value.This paper adopts a computer simulation method to topologically design a series of organic porous aromatic framework materials（PAFs）,and studies their gas adsorption performance,which provides theoretical support for the further development and application of PAFs materials.The main content and innovative points are as follows:（1）In carbon allotropes,the natural tetrahedral carbon topology exists in diamond and lonsdaleite crystals.Based on the diamond and lonsdaleite topology,28 organic building units were used to construct PAFs crystal structures by the To Ba CCO program,followed by all structures were optimized with molecular force fields and semi-empirical method,thus a database containing 56 PAFs structures was constructed.Structural parameter calculations reveal that the surface areas of lonsdaleite-topology PAFs structure are slightly larger than that of diamond-topology,and the pore size distribution follows a multi-peak distribution with wider distribution.Using the grand canonical Monte Carlo（GCMC）method,the static adsorption properties of CH4,CO2 and H2 gases were investigated.Nine high-performance PAFs materials with CH4 adsorption capacities exceeding the U.S.Department of Energy（DOE）commercial target（180 v STP/v）were screened.Among them,the PAFs structure constructed based on the1,3,5-hexatriyne building unit with the lonsdaleite and diamond topologies exhibited the best CH4 storage performance,with deliverable capacities（DC）of 228.21 and 222.88 v STP/v,respectively,significantly higher than the DOE commercial target,and can be used as highly potential adsorbents for natural gas in vehicles.Additionally,the relationship between structural parameters and CH4 deliverable capacity was analyzed in detail.Moreover,the CO2 and H2adsorption properties of the 56 PAFs materials were also investigated.It was found that most of the CO2 and H2 adsorption properties of the constructed PAFs materials exceeded PAF-1.The 1,3,5-hexatriynyl PAFs also exhibited the highest CO2 and H2 adsorption,about twice that of PAF-1.We also noted that PAFs materials exhibited different gas adsorption properties by using the same building unit based on lonsdaleite and diamond topologies（2）In order to further analyze the influence factors of topology on gas adsorption performance and screen for better tetrahedral topology,we constructed a database of 209 PAFs materials crystal structures based on the best 1,3,5-hexatriyne organic building units selected by using the To Ba CCo program.The 209 tetrahedral topologies came from SACADA database（26 types）and machine learning methods to select tetrahedral topologies with low energy（183types）.Structural characterization reveals that most of the 1,3,5-hexatriyne-based tetrahedral PAFs exhibits accessible surface area distribution in the range of 9000-10000m2g-1,with pore limiting diameter distributions in the range of 10-15（?）,and largest cavity diameter distributions in the range of 15-20（?）.Using grand canonical Monte Carlo（GCMC）methods,the CH4 gas adsorption performances of 209 topological PAFs were studied,and 11 types of CH4 with adsorption capacities greater than that of the 1,3,5-hexatriyne-based diamond topology PAF（222.88 v STP/v）were screened.Among them,the tetrahedral topology qtz-PAF had a high DC value of 238.6 v STP/v and could be a potential adsorbent for natural gas in vehicles. |
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