## 3 Calculation  
The new model of Equation (8) was used to correlate the dynamic viscosity of glasses, from \(T_{g}\) to higher temperatures. Because the viscosity in the high-temperature region is more easily measured than the viscosity at the low-temperature region, the experimental viscosity data at high temperatures can be fitted to Equation (8), and \(C\), \(D\), \(H\), and \(\beta\) are obtained. Then, the model is extrapolated to predict the low-temperature viscosity. The nonlinear regression method was employed and implemented by using MATLAB. An example of a calculation is given by fitting Equation (8) to the viscosity data of 7.9 Cs\({}_{2}\)O-23.2 CaO-66.7 SiO\({}_{2}\)-1 Fe\({}_{2}\)O\({}_{3}\) (mol%) from the literature [38]. The corresponding data are plotted in Figure 2a, where the data in the red circle came from fitting results. The same regression method was also applied in three other classic models--VFT, AM, and MYEGA--and their predictions were compared in the low-temperature range. Three expressions are written in terms of fragility [16]:  
VFT:  
\[\log_{10}\eta(T)=\log_{10}\eta_{\infty}+\frac{\left(12-\log_{10}\eta_{\infty} \right)^{2}}{m\left(\frac{T}{T_{g}}-1\right)+\left(12-\log_{10}\eta_{\infty} \right)}. \tag{9}\]  
AM:  
\[\log_{10}\eta(T)=\log_{10}\eta_{\infty}+\left(12-\log_{10}\eta_{\infty}\right) \left(\frac{T_{g}}{T}\right)^{m/(12-\log_{10}\eta_{\infty})} \tag{10}\]  
Figure 2: (a) Viscosity data of 7.9 Cs\({}_{2}\)O-23.2 CaO-66.7 SiO\({}_{2}\)-1 Fe\({}_{2}\)O\({}_{3}\) (the data in the red circle are for fitting); (b) results of the low-temperature extrapolation of the four models. MYEGA:  
\[\log_{10}\eta(T)=\log_{10}\eta_{\infty}+\big{(}12-\log_{10}\eta_{\infty}\big{)} \frac{Tg}{T}\exp\left[\bigg{(}\frac{m}{12-\log_{10}\eta_{\infty}}-1\bigg{)} \bigg{(}\frac{T_{g}}{T}-1\bigg{)}\right] \tag{11}\]  
where \(\eta_{\infty}\) is infinite temperature viscosity and m is fragility. The parameters are listed in Table 1. Figure 2b illustrates temperature dependence of the viscosity of 7.9 Cs\({}_{2}\)O-23.2 CaO-66.7 SiO\({}_{2}\)-1 Fe\({}_{2}\)O\({}_{3}\). According to the previous research, the VFT model always overpredicts the values of viscosity at low temperatures [13; 39], especially for the liquids with high fragility [16]. Clearly, none of the results predicted at a low-temperature (1010 to 1100 K) extrapolation of the four models is close to the experimental data. It shows that the fitting method has a direct impact on the final prediction. How to accurately estimate the log\(\eta\) versus T function at low temperatures is a tough problem. The most widely accepted definition of \(T_{g}\) is raised by [PERSON], who defined \(T_{g}\) as the corresponding temperature when the value of viscosity is equal to \(10^{12}\) Pa-s [40]. \(T_{g}\) can be measured by simple thermal analysis. Therefore, we treat the points as fitting data as shown in Figure 3a. The predicted results are significantly improved, especially the predicted values of high-viscosity, are in good agreement with the experimental results. Coefficients of determination (\(R^{2}\)) listed in Table 2 are all over 0.999. Meanwhile, it is found that the obtained log\(\eta_{\infty}\) and m from different models by the same fitting method also have a certain difference, especially log\(\eta_{\infty}\). It shows that more errors occur when using different models of the same parameter. Viscosity is often affected by many factors that impact obvious limitations on viscosity modeling, such as thermal history, composition, etc. Note that this study does not focus on comparing the physical significance of these models. Following this work, the viscosity data of other glass compositions are further validated through this modified Eyring model. The viscosity data of different glasses were collected, including borate [41],