Data Sources and Citation Metrics
The 5th edition of the Research.com Best Chemistry Scientists in Portugal Ranking is primarily based on bibliometric data sourced from OpenAlex and CrossRef, complemented by multiple other authoritative data sources. These databases are recognized for their comprehensive coverage and reliability, providing detailed information on publications, citations, and author profiles. The bibliometric data used to devise the citation-based metrics for this ranking were collected on January 12, 2026.
The position of each scientist in the ranking is determined by their D-index (Discipline H-index). Unlike the traditional H-index, the D-index is discipline-specific and includes only papers and citation metrics pertinent to the examined field—in this case, Chemistry. This focused approach ensures that the ranking reflects research impact within the relevant scientific domain.
Scope of Research and Qualification Criteria
The ranking process began with the examination of 279,971 scientist profiles identified across all disciplines from diverse bibliometric repositories. Within this extensive dataset, 152 scientists specializing in Chemistry were specifically evaluated for inclusion.
To qualify for the Chemistry ranking, a scientist’s D-index was required to be at least 40, with a majority of their tier publications firmly within the domain of Chemistry. Additionally, awards and other significant achievements reported in the field were taken into consideration as supplementary qualitative indicators.
The D-index threshold is carefully calibrated as increments of 10, dependent on the estimated total number of scholars in each discipline. This approach guarantees the inclusion of approximately the top 1% of leading researchers within the list. Furthermore, a proximity criterion is applied whereby the difference between a scientist’s overall H-index and their Chemistry-specific D-index must not exceed 30%, ensuring alignment between general scholarly output and discipline-focused impact.
Additional Verification Practices
The Research.com team acknowledges that raw bibliometric data alone cannot provide a definitive evaluation of scholarly impact. Consequently, all scientist profiles were subjected to meticulous manual verification and cross-correlation against publications indexed in a broad array of trustworthy sources.
While not influencing the researcher’s numerical position in the ranking, the total number of papers published in prominent journals and conference proceedings is recognized as a valuable secondary signal of a scientist’s contribution to their field. This consideration enhances the credibility and contextual understanding of the rankings.
Overall, the ranking position is established using the D-index computed from information gathered primarily from OpenAlex and CrossRef—the most prominent and trusted bibliometric databases available to the global research community. For a comprehensive understanding of the methodology and criteria employed, readers are encouraged to visit our methodology page.
Research.com’s Mission and Vision
Research.com is committed to motivating researchers, industry leaders, and policymakers worldwide to monitor and understand the trajectories of leading scientific experts. This ranking serves as a valuable tool for the global scientific community, enabling individuals, institutions, and governments to readily identify top experts in specific fields, countries, or research organizations.
By providing a transparent, carefully curated, and data-driven listing, Research.com aims to foster greater collaboration, informed decision-making, and enhanced recognition of outstanding scientific contributions in Chemistry and beyond.
