How VU’s Supercomputer Unites Hundreds of Computers for a Single Task

Assoc. Prof. Mindaugas Mačernis. Photo: VU.

Modern physics is an incredibly complex endeavour, where conducting research and calculations is impossible without top-tier equipment. One such device, the supercomputer at Vilnius University (VU), is among the most powerful scientific instruments in Lithuania, enabling researchers in physics, chemistry, and other fields to solve problems that would be impossible to crack without it. Associate Professor Mindaugas Mačernis, the head of the “HPC Saulėtekis” centre, quantum chemistry researcher, and populariser of quantum biology, says that supercomputers are changing not only the scientific process itself but also the very understanding of what modern physicists must be capable of.

Incomparably More Powerful Than Regular Computers or Phones

VU’s supercomputer operates in the National Center for Physical and Technological Sciences (NFTMC) building, which houses two institutions – VU and the Center for Physical Sciences and Technology (FTMC). You’ll hear the device in the VU Faculty of Physics scientific facilities before you see it. The country’s most powerful computing system sits in a carefully secured room, continuously cooled by a specialised liquid system – without it, the machine would simply overheat and become unusable.

According to Assoc. Prof. M. Mačernis, one of the supercomputer’s architects who also works at the Institute of Chemical Physics, believes that having the supercomputer became an inevitable necessity for the university’s scientific community. In modern quantum chemistry, substantial computational resources are essential to achieve new and interesting results.

“At first, we needed to figure out how to create our own device. That’s how it all started. Initially, we had just one server. We gradually improved it by learning from both global experience, where quantum chemistry researchers have long worked with powerful supercomputers, and our own trial-and-error. We grew step by step – we took on increasingly complex tasks, acquired better equipment, developed more of our own expertise,” he says.

VU’s supercomputer can be called a traditional computing system. In terms of power, it’s classified as medium – about 7,000 times weaker than the world’s most powerful supercomputer. Yet such an assessment is fairly relative: if you compare it with the most expensive laptop you can buy in a store, it will be at least dozens, if not hundreds, of times more powerful. This means calculations can be performed incomparably faster and at much larger scales.

Photo: VU.

“It’s important to understand how significant the interaction of all supercomputer elements is. Quantum chemistry or molecular dynamics calculations require high processor clock frequencies, large amounts of memory, the ability to connect all processors, and the ability to write data to disk systems quickly. If even one element is slower, problems arise. Tasks can become unsolvable or their solution significantly slows down,” explains Assoc. Prof. M. Mačernis.

Modern Physicists Must Also Be Programmers

At VU’s Institute of Chemical Physics, the supercomputer is used not only by university colleagues but also by scientists from across Lithuania. Most commonly, it is used to solve quantum chemistry and molecular dynamics problems, but astrophysicists and physicists from other fields also regularly expand their competencies. The supercomputer is also used in international “Horizon”, “Eureka”, and “DIGITAL” projects.

Assoc. Prof. M. Mačernis emphasises that support from the Ministry of Education, Science, and Sports was crucial in developing the supercomputer. Without it, Lithuania would have had much more difficulty becoming a member of the EGI cloud and EuroHPC supercomputer infrastructure. Moreover, through the development of the competence center (NCC Lithuania), Lithuania became a world-class player in the computing field.

It’s essential to keep in mind that even such a powerful system doesn’t provide benefits on its own. You still need to know how to use it. The supercomputer can solve the same problem in either a day or an hour. Everything depends on how the scientist formulates it. Properly utilising a supercomputer’s memory, managing resources, and getting answers promptly require specialised knowledge and skills. In other words, two connected computers won’t necessarily calculate twice as fast. On the contrary, they can be even twice as slow, especially if there’s a lack of real experience and understanding.

“For example, for everything to work as it should, the program code cannot have more than 1 per cent non-parallel code. This means that, out of 100 lines, only one can be dedicated to a specific processor. In other words, for smooth operation, processors must execute the same instructions simultaneously. You can imagine how long it takes to prepare the task itself and how important it is. This requires excellent programming skills,” assures one of VU’s supercomputer architects.

According to him, such abilities will only become increasingly important for researchers in the future. Already, almost every laboratory strives to acquire at least a minimal-capability supercomputer-class server. Computational physics has become the third branch of this science, alongside theoretical and experimental physics. It allows simulating complex systems and modelling experiments that would otherwise be practically impossible to perform.

Photo: VU.

“In this field, it would simply be impossible to work without computers, and to work efficiently, you must be able to coordinate and understand how processes occur both at the hardware and software levels. In other words, it’s a very complex task that requires solving while considering all components. And imagine, at the same time, I’m still trying to comprehend the mysteries of quantum biology...” says Assoc. Prof. M. Mačernis.

In the future, computational physics should reach a new level with the advent of quantum computers. Although a universal quantum computer still seems like a fairly distant prospect, its principles are already being used – for example, in financial technologies or cryptography. However, the real breakthrough would be the ability to solve problems that even supercomputers currently cannot solve.

“The famous Richard Feynman urged solving quantum problems with quantum computers. Yes, for now, we only have ideas and beginnings of how to write algorithms for such devices, but physicists can already examine quantum phenomena such as superposition and quantum entanglement. The fact is that the principle itself works and can be used. Now it’s just a matter of time before we find suitable technologies,” believes the VU Faculty of Physics scientist.