VaPOrS v1.0.1: An automated model for estimating vapor pressure of organic compounds using SMILES notation

Abstract. Volatile organic compounds play a significant role in atmospheric chemistry, influencing air quality and climate change. Accurate prediction of their physical properties is essential for understanding their behavior. This paper introduces the VaPOrS (Vapor Pressure in Organics via SMILES) as a comprehensive tool designed to process SMILES notation of organic compounds, identify key functional groups, and calculate their saturation vapor pressure and enthalpy of vaporization at any specified temperature. While this first study focuses on applying the SIMPOL method for parameterization, VaPOrS is inherently adaptable to other structure-based parameterization approaches, such as group additivity and volatility basis set (VBS) methods by extracting substructure information from each string that is meaningful to property predictive techniques. It can also be extended to any thermodynamic property that relies on structural group-based parameterizations. In its current version, the tool automates the detection of 30 critical structural groups and has been validated against manually counted functional groups and experimental saturation vapor pressure data for a diverse set of compounds. The results demonstrate high accuracy, with the tool correctly identifying the same functional groups, followed by providing prompt saturation vapor pressure predictions according to the SIMPOL parameterization. The developed method can be integrated into large-scale simulation models targeting secondary aerosol formation and involving thousands of organic species at once. Thus, the developed tool offers a robust computational approach for research in atmospheric chemistry and environmental science, allowing to streamline the analysis of a large collection of organic compounds, aiding in the assessment of their climatic impacts.