A1 - Szukowski G. A2 - Bieliński M., Kamienairz G. PB - OWN N2 - The paper presents the algorithm for calculation of the maximum eigenvalue of the transfer matrix for one-dimensional S=1/2 Heisenberg model with nearest and next-nearest neighbours interactions. This value permits a calculation of the partition function and free energy of the quantum system. This algorithm is implemented in the mevnnn procedure written in FORTRAN 90. The procedure is available at the Poznań Supercomputing and Networking Center on Cray T3E supercomputer in the library / u s r / l o c a l / l i b / l i b m s . a L1 - http://lib.psnc.pl/Content/531/10.12921_cmst.2002.08.01.97-101_Szukowski.pdf L2 - http://lib.psnc.pl/Content/531 CY - Poznań ER - UR - http://lib.psnc.pl/dlibra/docmetadata?id=531