Install libpdflib804-2-gfortran by entering the following commands in the terminal:
sudo apt update sudo apt install libpdflib804-2-gfortran
[Physics] Comprehensive library of parton density functions
The PDFLIB package gathers about 100 different sets of Parton Density Functions into a comprehensive library in a consistent way. Density functions are available for the nucleon, pion and photon. The library also allows the calculation of the strong force coupling constant to first or second order at a given value of Q-squared. . Note that in order to compile and link programs against this library, you must also install the libpdflib804-2-dev package.