VeloxChem/VeloxChem
Nov 2024 – Mar 2026
10 Months active
Languages Used
C++MakefilePythonNumpyCShellCMakehpp
Technical Skills
C++C++ DevelopmentCode RefactoringComputational ChemistryFortran (implied by numerical methods)High-Performance Computing
Zilvinas Rinkevicius
PROFILE
Zilvinas Rinkevicius
Over ten months, contributed to VeloxChem by developing advanced features for quantum chemistry simulations, focusing on electron repulsion integrals, Fock matrix construction, and effective core potential frameworks. Leveraging C++, Python, and Fortran, implemented high-performance algorithms for geometrical derivatives, parallelized matrix computations with OpenMP, and expanded support for range-separated and projected ECP calculations. Enhanced the build system using Makefile and CMake, improving portability and continuous integration reliability. Emphasized test-driven development, introducing robust unit tests and CI enhancements to ensure numerical accuracy and stability. This work enabled more accurate molecular modeling, scalable simulations, and maintainable scientific computing infrastructure within the repository.
Overall Statistics
Feature vs Bugs
93%Features
Repository Contributions
91Total
Bugs
2
Commits
91
Features
28
Lines of code
4,967,881
Activity Months10
Your Network
101 peopleSame Organization
@kth.se32
Shared Repositories
69
Work History
March 2026
19 Commits • 1 Features
Mar 1, 2026March 2026 VeloxChem monthly performance summary: Implemented a comprehensive Projection Core Potentials and Local ECP Gradient Derivatives Framework enabling gradients, higher-order derivatives, Hessians, and derivative matrices across bra/ket sides; stabilized numerical kernels (Bessel/Gamma handling) and edge-case behavior; restructured ECP recursions to VRRs; introduced derivative driver classes; expanded test coverage and derivative support up to 200 derivatives across projectors.
19 Commits • 1 Features
Mar 1, 2026March 2026 VeloxChem monthly performance summary: Implemented a comprehensive Projection Core Potentials and Local ECP Gradient Derivatives Framework enabling gradients, higher-order derivatives, Hessians, and derivative matrices across bra/ket sides; stabilized numerical kernels (Bessel/Gamma handling) and edge-case behavior; restructured ECP recursions to VRRs; introduced derivative driver classes; expanded test coverage and derivative support up to 200 derivatives across projectors.
March 2026
February 2026
4 Commits • 2 Features
Feb 1, 2026February 2026 (VeloxChem/VeloxChem) focused on reliability, expanded core-potential capabilities, and strengthened testing/CI for faster, more reproducible deliveries. Key outcomes include a bug fix for Bessel recursion symmetry improving electronic-structure accuracy, expanded projected ECP support up to G functions and G projectors, and enhanced testing for def2-TZVPP AuH2 and GdH3 with Py3.14 compatibility. These changes increase simulation accuracy, broaden system coverage, and reduce build/test friction to accelerate development cycles.
February 2026
4 Commits • 2 Features
Feb 1, 2026February 2026 (VeloxChem/VeloxChem) focused on reliability, expanded core-potential capabilities, and strengthened testing/CI for faster, more reproducible deliveries. Key outcomes include a bug fix for Bessel recursion symmetry improving electronic-structure accuracy, expanded projected ECP support up to G functions and G projectors, and enhanced testing for def2-TZVPP AuH2 and GdH3 with Py3.14 compatibility. These changes increase simulation accuracy, broaden system coverage, and reduce build/test friction to accelerate development cycles.
October 2025
8 Commits • 4 Features
Oct 1, 2025Month: 2025-10 | VeloxChem/VeloxChem Concise monthly summary focusing on business value and technical achievements across features, bugs, and performance improvements.
8 Commits • 4 Features
Oct 1, 2025Month: 2025-10 | VeloxChem/VeloxChem Concise monthly summary focusing on business value and technical achievements across features, bugs, and performance improvements.
October 2025
September 2025
7 Commits • 2 Features
Sep 1, 2025Sep 2025 VeloxChem delivered substantial accuracy and foundation work: advanced geometrical derivatives for electron repulsion integrals (ERIs) with F-basis functions, including support for range-separated calculations, and a foundational RI-JK Fock driver. These efforts enhance geometry optimization accuracy, enable range-separated treatments, and establish a foundation for faster, scalable Fock-matrix construction. Build/config robustness was improved to support the new capabilities, setting the stage for future performance improvements on larger systems.
September 2025
7 Commits • 2 Features
Sep 1, 2025Sep 2025 VeloxChem delivered substantial accuracy and foundation work: advanced geometrical derivatives for electron repulsion integrals (ERIs) with F-basis functions, including support for range-separated calculations, and a foundational RI-JK Fock driver. These efforts enhance geometry optimization accuracy, enable range-separated treatments, and establish a foundation for faster, scalable Fock-matrix construction. Build/config robustness was improved to support the new capabilities, setting the stage for future performance improvements on larger systems.
May 2025
1 Commits • 1 Features
May 1, 2025May 2025 (VeloxChem/VeloxChem) — Focused on build-system modernization by removing BLAS/OpenBLAS configuration from Makefile.setup, reducing build complexity and eliminating environment-specific include paths and library links for OpenBLAS. This change simplifies maintenance, improves portability across environments, and lays groundwork for future modular dependencies. Commit f3dec70cfc5bd41173fca57f2109a56cd942f7db documents the removal of BLAS/LAPPACK from Makefile.setup. No major bug fixes were logged this month; the effort prioritized build stability and developer onboarding. Technologies demonstrated: Makefile-driven build configuration, dependency management, and cross-environment portability.
1 Commits • 1 Features
May 1, 2025May 2025 (VeloxChem/VeloxChem) — Focused on build-system modernization by removing BLAS/OpenBLAS configuration from Makefile.setup, reducing build complexity and eliminating environment-specific include paths and library links for OpenBLAS. This change simplifies maintenance, improves portability across environments, and lays groundwork for future modular dependencies. Commit f3dec70cfc5bd41173fca57f2109a56cd942f7db documents the removal of BLAS/LAPPACK from Makefile.setup. No major bug fixes were logged this month; the effort prioritized build stability and developer onboarding. Technologies demonstrated: Makefile-driven build configuration, dependency management, and cross-environment portability.
May 2025
March 2025
12 Commits • 3 Features
Mar 1, 2025March 2025 monthly summary for VeloxChem/VeloxChem: Delivered expanded electron repulsion integral (ERI) capabilities; implemented direct RI gradient calculations and excited-state gradient support; established MPI-based distribution and build-system improvements for RI/FockDriver; and strengthened testing and numerical accuracy with symmetry and threshold fixes. These efforts broaden ERI coverage, improve gradient accuracy and performance, and enable scalable, MPI-driven workflows for larger systems.
March 2025
12 Commits • 3 Features
Mar 1, 2025March 2025 monthly summary for VeloxChem/VeloxChem: Delivered expanded electron repulsion integral (ERI) capabilities; implemented direct RI gradient calculations and excited-state gradient support; established MPI-based distribution and build-system improvements for RI/FockDriver; and strengthened testing and numerical accuracy with symmetry and threshold fixes. These efforts broaden ERI coverage, improve gradient accuracy and performance, and enable scalable, MPI-driven workflows for larger systems.
February 2025
13 Commits • 4 Features
Feb 1, 2025February 2025 at VeloxChem/VeloxChem delivered substantial correctness, performance, and capability improvements across RI and ERI workflows. Key deliverables include: (1) RI OpenMP region fixes establishing task-local variables and correct data sharing to eliminate race conditions; (2) RI gradient calculations enhancements with a new gradient driver, corrected angular momentum support, and SIMD-accelerated derivatives; (3) T3C integral expansion with broader angular momentum coverage and new geometry buffers plus CT3RectFlatBuffer storage and geometry driver; (4) build/test/debug workflow improvements for Python/OpenMP builds and CI troubleshooting; (5) spherical momentum code updates expanding angular momentum coverage with new transformation factors and improved rescale/overlap logic. These changes reduce risk, improve accuracy, and set the stage for faster, more reliable simulations and CI feedback.
13 Commits • 4 Features
Feb 1, 2025February 2025 at VeloxChem/VeloxChem delivered substantial correctness, performance, and capability improvements across RI and ERI workflows. Key deliverables include: (1) RI OpenMP region fixes establishing task-local variables and correct data sharing to eliminate race conditions; (2) RI gradient calculations enhancements with a new gradient driver, corrected angular momentum support, and SIMD-accelerated derivatives; (3) T3C integral expansion with broader angular momentum coverage and new geometry buffers plus CT3RectFlatBuffer storage and geometry driver; (4) build/test/debug workflow improvements for Python/OpenMP builds and CI troubleshooting; (5) spherical momentum code updates expanding angular momentum coverage with new transformation factors and improved rescale/overlap logic. These changes reduce risk, improve accuracy, and set the stage for faster, more reliable simulations and CI feedback.
February 2025
January 2025
10 Commits • 6 Features
Jan 1, 2025January 2025 monthly summary for VeloxChem/VeloxChem focused on delivering core methodological enhancements and scalable infrastructure. Highlights include: (1) Nuclear potential gradient range-separated updates with removal of double scaling factors, improving accuracy and consistency across calculations; (2) mixed-precision groundwork introducing skeleton structures and overloads to support single and double precision, enabling potential performance and memory optimizations; (3) optimization of pressure integral gnorm factor initialization to reduce overhead and improve runtime performance; (4) implementation of two-center electron repulsion integrals (ERIs) capability with first-order geometric derivatives, including tests and driver updates for validation; (5) RI Fock driver and J-RI Fock matrix enhancements, including a working J-RI Fock implementation and Python bindings to broaden accessibility and scripting integration.
January 2025
10 Commits • 6 Features
Jan 1, 2025January 2025 monthly summary for VeloxChem/VeloxChem focused on delivering core methodological enhancements and scalable infrastructure. Highlights include: (1) Nuclear potential gradient range-separated updates with removal of double scaling factors, improving accuracy and consistency across calculations; (2) mixed-precision groundwork introducing skeleton structures and overloads to support single and double precision, enabling potential performance and memory optimizations; (3) optimization of pressure integral gnorm factor initialization to reduce overhead and improve runtime performance; (4) implementation of two-center electron repulsion integrals (ERIs) capability with first-order geometric derivatives, including tests and driver updates for validation; (5) RI Fock driver and J-RI Fock matrix enhancements, including a working J-RI Fock implementation and Python bindings to broaden accessibility and scripting integration.
December 2024
8 Commits • 4 Features
Dec 1, 2024December 2024 VeloxChem monthly summary: Delivered major feature work across electron repulsion geometry, nuclear potential integrals, range-separated electric field integrals, and atom core potentials. Key outcomes include 1010-derivative support for electron repulsion geometry with corrected autogenerated code and recursion fixes, updated headers and test data; introduction of a new 200-derivative nuclear potential integral with geometry refinements; first-derivative support for range-separated electric field integrals and nuclear potential; foundational data structures for atom core potentials (CAtomCorePotentia l, CBaseCorePotential) to enable scalable ECP data management; and inclusion of a mixed range-separation factor to improve numerical stability. These changes improve accuracy, stability, and extendibility for high-derivative simulations and advanced molecular modeling, delivering demonstrable business value through more precise simulations and longer-term maintainability.
8 Commits • 4 Features
Dec 1, 2024December 2024 VeloxChem monthly summary: Delivered major feature work across electron repulsion geometry, nuclear potential integrals, range-separated electric field integrals, and atom core potentials. Key outcomes include 1010-derivative support for electron repulsion geometry with corrected autogenerated code and recursion fixes, updated headers and test data; introduction of a new 200-derivative nuclear potential integral with geometry refinements; first-derivative support for range-separated electric field integrals and nuclear potential; foundational data structures for atom core potentials (CAtomCorePotentia l, CBaseCorePotential) to enable scalable ECP data management; and inclusion of a mixed range-separation factor to improve numerical stability. These changes improve accuracy, stability, and extendibility for high-derivative simulations and advanced molecular modeling, delivering demonstrable business value through more precise simulations and longer-term maintainability.
December 2024
November 2024
9 Commits • 1 Features
Nov 1, 2024November 2024 VeloxChem monthly summary: Delivered second-order geometrical derivatives support for Electron Repulsion Integrals (ERIs) and Fock matrices across geom2000, geom1100, and geom1010, including new headers, calculation functions, and driver/test infrastructure. Expanded test coverage with mixed second-order derivatives and Hessian integrals; advanced higher angular momentum derivative integrations for ERIs; improved reliability of HRR-related labeling and contractions. Implemented a distributor for differentiated bra/ket density with symmetric density to ensure correct contractions. Updated integrals for (10|10) and refined labeling to prevent accidental reassignment in HRR recursions. These updates enable more accurate Hessian-based properties, better post-SCF workflows, and stronger code quality. Demonstrated skills in C++ core development, Python test harness, and test-driven validation.
November 2024
9 Commits • 1 Features
Nov 1, 2024November 2024 VeloxChem monthly summary: Delivered second-order geometrical derivatives support for Electron Repulsion Integrals (ERIs) and Fock matrices across geom2000, geom1100, and geom1010, including new headers, calculation functions, and driver/test infrastructure. Expanded test coverage with mixed second-order derivatives and Hessian integrals; advanced higher angular momentum derivative integrations for ERIs; improved reliability of HRR-related labeling and contractions. Implemented a distributor for differentiated bra/ket density with symmetric density to ensure correct contractions. Updated integrals for (10|10) and refined labeling to prevent accidental reassignment in HRR recursions. These updates enable more accurate Hessian-based properties, better post-SCF workflows, and stronger code quality. Demonstrated skills in C++ core development, Python test harness, and test-driven validation.
Activity
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Quality Metrics
Correctness88.0%
Maintainability81.8%
Architecture83.0%
Performance75.6%
AI Usage22.0%
Skills & Technologies
Programming Languages
CC++CMakeFortranMakefileNumpyPythonShellYAMLhpp
Technical Skills
Build SystemBuild System ConfigurationBuild SystemsC++C++ DevelopmentC++ developmentC++ programmingCMakeCode RefactoringCompilationComputational ChemistryComputational PhysicsData StructuresDebuggingDriver Implementation
Repositories Contributed To
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