# Molecular Dynamics Simulation of Bulk Cu Material under Various Factors
## 1 Introduction  
Metals are the most used materials, and they are readily available in nature. Among them, copper (Cu) is a metal with an atomic number of \(Z\) = 29 with outstanding properties, such as high ductility and good thermal and electrical conductivity [1; 2; 3; 4; 5; 6; 7], and it is a soft, ductile, orange-red metal. Therefore, Cu is widely used in human life and science and technology; for example, one can produce materials that effectively conduct heat and electricity [8], Cu thin films indispensable in electronics [9; 10; 11], phosphorescent materials [12], etc. As a consequence, for a long time, Cu has been a center of interest for many researchers, both in theoretical and experimental terms [13; 14; 15]. Experimental methods include direct MW irradiation in the presence of triethylene-tramine (TETA) [16], sliding friction plate strain [17], and the reduction method [18; 19; 20]. Instruments such as scanning electron microscopes (SEMs) and transmission electron microscopes (TEMs) are called electron microscopes (SEM/TEM) and are used to observe the surface details of materials, while the melting and crystallization temperatures are directly measured by differential scanning calorimetry (DSC), X-ray diffraction, optical microscopy, and electron microscopy [16]. [PERSON] et al. [16] successfully studied the melting and crystallization process and determined the phase transition temperature (T\({}_{\rm m}\)) to be T\({}_{\rm m}\) = 1358 K. In addition, it can be noted that Cu with a size less than 100 nm can be MW irradiated (microwave) with or without polyols [21; 22]. Theoretically, results showed that for 5 nm materials, a significant decrease in the phase transition temperature T\({}_{\rm m}\) to several hundred degrees for metals was produced. Furthermore, if the Cu material has a size of less than 3 nm, the T\({}_{\rm m}\) decreases sharply (T\({}_{\rm m}\) < 373 K) because of the size effect (surface effect) [23]. Recently, [PERSON] et al. [24]successfully determined the gradient of Cu through SMGT and grain size dependences of grain boundary (GB) migration in nanogenized Ag, Cu, and Ni under tension. The thin tissue molecular dynamics (MD) method [25] is a modern method used to determine properties, such as the Radial Distribution Function (RDF) [26; 27], the transformation between local structures by Honeycutt-Andersen (HA) [28], local atomic shear strain [29; 30], and pick separation at the second peak of RDF of the material [31; 32]. To determine all these characteristics, it is necessary to use suitable interaction potentials and to apply the Embedded Atom Method (EAM). [PERSON] et al. [33] determined the structural stability and lattice defects in copper. Among the research methods, simulation methods are considered to be the most effective research tools today because they have the ability to approach the critical size and reach regions with high temperatures and pressure (such as 360 GPa and 7000 K for MgSiO\({}_{3}\)[34] and CaSiO\({}_{3}\)[35]) that experimental methods cannot approach. The authors of references [36; 37; 38] considered numerically by MD simulation the atomic structure variations in the cooling, vitrification, and crystallization process in liquid metals. The process consists of continuous cooling and isothermal annealing. The numerical calculations are performed in the framework of an embedded-atom method potential at constant pressure. A direct structure observation has been observed in the large simulation cells that contain about \(10^{5}\) to \(10^{6}\) atoms. MD simulation of glass transition of pure metals, such as Fe, Ni, Cu, and other metals, was made. The authors concluded that for the occurrence of crystallization, the cubic cell size was typically chosen to be about 10 nm. Researchers use a variety of tools, such as free commercial software or self-coding based on molecular dynamics simulation methods, such as the use of the Large-scale Atomic Molecular Massively Parallel Simulator (LAMMPS) program [39], to simulate the materials. [PERSON] et al.